diff --git a/bacnet-stack/config.h b/bacnet-stack/config.h
index 6af77078..0ef4934f 100644
--- a/bacnet-stack/config.h
+++ b/bacnet-stack/config.h
@@ -11,7 +11,7 @@
 /* Lon=206, MS/TP=480, ARCNET=480, Ethernet=1476 */
 #ifndef MAX_APDU
   /* #define MAX_APDU 50 */
-#define MAX_APDU 480
+  #define MAX_APDU 480
   /* #define MAX_APDU 1476 */
 #endif
 /* for confirmed messages, this is the number of transactions */
diff --git a/bacnet-stack/dlmstp.h b/bacnet-stack/dlmstp.h
index df327e0a..81726a9a 100644
--- a/bacnet-stack/dlmstp.h
+++ b/bacnet-stack/dlmstp.h
@@ -60,9 +60,6 @@ extern "C" {
     bool dlmstp_init(char *ifname);
     void dlmstp_cleanup(void);
 
-    /* address of the 16-bit timer.  Update it in an ISR or Task. */
-    volatile uint16_t *dlmstp_millisecond_timer_address(void);
-
     /* returns number of bytes sent on success, negative on failure */
     int dlmstp_send_pdu(BACNET_ADDRESS * dest,  /* destination address */
         BACNET_NPDU_DATA * npdu_data,   /* network information */
diff --git a/bacnet-stack/mstp.c b/bacnet-stack/mstp.c
index 5368b9f8..3cb4c4c8 100644
--- a/bacnet-stack/mstp.c
+++ b/bacnet-stack/mstp.c
@@ -213,7 +213,7 @@ void MSTP_Create_And_Send_Frame(volatile struct mstp_port_struct_t *mstp_port,
     RS485_Send_Frame(mstp_port,
         (uint8_t *)&mstp_port->OutputBuffer[0],
         len);
-    /* FIXME: be sure to reset SilenceTimer after each octet is sent! */
+    /* FIXME: be sure to reset SilenceTimer() after each octet is sent! */
 }
 
 void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
@@ -227,7 +227,7 @@ void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
         mstptext_receive_state(mstp_port->receive_state),
         mstp_port->DataRegister, mstp_port->HeaderCRC, mstp_port->Index,
         mstp_port->EventCount, mstp_port->DataLength,
-        mstp_port->SilenceTimer);
+        mstp_port->SilenceTimer();
 #endif
     switch (mstp_port->receive_state) {
         /* In the IDLE state, the node waits for the beginning of a frame. */
@@ -235,7 +235,7 @@ void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
         /* EatAnError */
         if (mstp_port->ReceiveError == true) {
             mstp_port->ReceiveError = false;
-            mstp_port->SilenceTimer = 0;
+            mstp_port->SilenceTimerReset();
             INCREMENT_AND_LIMIT_UINT8(mstp_port->EventCount);
             /* wait for the start of a frame. */
             mstp_port->receive_state = MSTP_RECEIVE_STATE_IDLE;
@@ -253,7 +253,7 @@ void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
             /* Preamble1 */
             if (mstp_port->DataRegister == 0x55) {
                 mstp_port->DataAvailable = false;
-                mstp_port->SilenceTimer = 0;
+                mstp_port->SilenceTimerReset();
                 INCREMENT_AND_LIMIT_UINT8(mstp_port->EventCount);
                 /* receive the remainder of the frame. */
                 mstp_port->receive_state = MSTP_RECEIVE_STATE_PREAMBLE;
@@ -264,7 +264,7 @@ void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
                 fprintf(stderr, "\n");
 #endif
                 mstp_port->DataAvailable = false;
-                mstp_port->SilenceTimer = 0;
+                mstp_port->SilenceTimerReset();
                 INCREMENT_AND_LIMIT_UINT8(mstp_port->EventCount);
                 /* wait for the start of a frame. */
                 mstp_port->receive_state = MSTP_RECEIVE_STATE_IDLE;
@@ -274,7 +274,7 @@ void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
         /* In the PREAMBLE state, the node waits for the second octet of the preamble. */
     case MSTP_RECEIVE_STATE_PREAMBLE:
         /* Timeout */
-        if (mstp_port->SilenceTimer > Tframe_abort) {
+        if (mstp_port->SilenceTimer() > Tframe_abort) {
             /* a correct preamble has not been received */
             /* wait for the start of a frame. */
             mstp_port->receive_state = MSTP_RECEIVE_STATE_IDLE;
@@ -282,7 +282,7 @@ void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
         /* Error */
         else if (mstp_port->ReceiveError == true) {
             mstp_port->ReceiveError = false;
-            mstp_port->SilenceTimer = 0;
+            mstp_port->SilenceTimerReset();
             INCREMENT_AND_LIMIT_UINT8(mstp_port->EventCount);
             /* wait for the start of a frame. */
             mstp_port->receive_state = MSTP_RECEIVE_STATE_IDLE;
@@ -293,7 +293,7 @@ void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
             /* Preamble2 */
             if (mstp_port->DataRegister == 0xFF) {
                 mstp_port->DataAvailable = false;
-                mstp_port->SilenceTimer = 0;
+                mstp_port->SilenceTimerReset();
                 INCREMENT_AND_LIMIT_UINT8(mstp_port->EventCount);
                 mstp_port->Index = 0;
                 mstp_port->HeaderCRC = 0xFF;
@@ -303,7 +303,7 @@ void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
             /* ignore RepeatedPreamble1 */
             else if (mstp_port->DataRegister == 0x55) {
                 mstp_port->DataAvailable = false;
-                mstp_port->SilenceTimer = 0;
+                mstp_port->SilenceTimerReset();
                 INCREMENT_AND_LIMIT_UINT8(mstp_port->EventCount);
                 /* wait for the second preamble octet. */
                 mstp_port->receive_state = MSTP_RECEIVE_STATE_PREAMBLE;
@@ -311,7 +311,7 @@ void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
             /* NotPreamble */
             else {
                 mstp_port->DataAvailable = false;
-                mstp_port->SilenceTimer = 0;
+                mstp_port->SilenceTimerReset();
                 INCREMENT_AND_LIMIT_UINT8(mstp_port->EventCount);
                 /* wait for the start of a frame. */
                 mstp_port->receive_state = MSTP_RECEIVE_STATE_IDLE;
@@ -321,20 +321,20 @@ void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
         /* In the HEADER state, the node waits for the fixed message header. */
     case MSTP_RECEIVE_STATE_HEADER:
         /* Timeout */
-        if (mstp_port->SilenceTimer > Tframe_abort) {
+        if (mstp_port->SilenceTimer() > Tframe_abort) {
             /* indicate that an error has occurred during the reception of a frame */
             mstp_port->ReceivedInvalidFrame = true;
             /* wait for the start of a frame. */
             mstp_port->receive_state = MSTP_RECEIVE_STATE_IDLE;
 #if PRINT_ENABLED_RECEIVE_ERRORS
             fprintf(stderr,"MSTP: Rx Header: SilenceTimer %d > %d\n",
-                mstp_port->SilenceTimer, Tframe_abort);
+                mstp_port->SilenceTimer(), Tframe_abort);
 #endif
         }
         /* Error */
         else if (mstp_port->ReceiveError == true) {
             mstp_port->ReceiveError = false;
-            mstp_port->SilenceTimer = 0;
+            mstp_port->SilenceTimerReset();
             INCREMENT_AND_LIMIT_UINT8(mstp_port->EventCount);
             /* indicate that an error has occurred during the reception of a frame */
             mstp_port->ReceivedInvalidFrame = true;
@@ -349,7 +349,7 @@ void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
 #endif
             /* FrameType */
             if (mstp_port->Index == 0) {
-                mstp_port->SilenceTimer = 0;
+                mstp_port->SilenceTimerReset();
                 INCREMENT_AND_LIMIT_UINT8(mstp_port->EventCount);
                 mstp_port->HeaderCRC =
                     CRC_Calc_Header(mstp_port->DataRegister,
@@ -361,7 +361,7 @@ void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
             }
             /* Destination */
             else if (mstp_port->Index == 1) {
-                mstp_port->SilenceTimer = 0;
+                mstp_port->SilenceTimerReset();
                 INCREMENT_AND_LIMIT_UINT8(mstp_port->EventCount);
                 mstp_port->HeaderCRC =
                     CRC_Calc_Header(mstp_port->DataRegister,
@@ -373,7 +373,7 @@ void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
             }
             /* Source */
             else if (mstp_port->Index == 2) {
-                mstp_port->SilenceTimer = 0;
+                mstp_port->SilenceTimerReset();
                 INCREMENT_AND_LIMIT_UINT8(mstp_port->EventCount);
                 mstp_port->HeaderCRC =
                     CRC_Calc_Header(mstp_port->DataRegister,
@@ -385,7 +385,7 @@ void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
             }
             /* Length1 */
             else if (mstp_port->Index == 3) {
-                mstp_port->SilenceTimer = 0;
+                mstp_port->SilenceTimerReset();
                 INCREMENT_AND_LIMIT_UINT8(mstp_port->EventCount);
                 mstp_port->HeaderCRC =
                     CRC_Calc_Header(mstp_port->DataRegister,
@@ -397,7 +397,7 @@ void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
             }
             /* Length2 */
             else if (mstp_port->Index == 4) {
-                mstp_port->SilenceTimer = 0;
+                mstp_port->SilenceTimerReset();
                 INCREMENT_AND_LIMIT_UINT8(mstp_port->EventCount);
                 mstp_port->HeaderCRC =
                     CRC_Calc_Header(mstp_port->DataRegister,
@@ -409,7 +409,7 @@ void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
             }
             /* HeaderCRC */
             else if (mstp_port->Index == 5) {
-                mstp_port->SilenceTimer = 0;
+                mstp_port->SilenceTimerReset();
                 INCREMENT_AND_LIMIT_UINT8(mstp_port->EventCount);
                 mstp_port->HeaderCRC =
                     CRC_Calc_Header(mstp_port->DataRegister,
@@ -480,7 +480,7 @@ void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
             /* not per MS/TP standard, but it is a case not covered */
             else {
                 mstp_port->ReceiveError = false;
-                mstp_port->SilenceTimer = 0;
+                mstp_port->SilenceTimerReset();
                 INCREMENT_AND_LIMIT_UINT8(mstp_port->EventCount);
                 /* indicate that an error has occurred during  */
                 /* the reception of a frame */
@@ -501,12 +501,12 @@ void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
         /* In the DATA state, the node waits for the data portion of a frame. */
     case MSTP_RECEIVE_STATE_DATA:
         /* Timeout */
-        if (mstp_port->SilenceTimer > Tframe_abort) {
+        if (mstp_port->SilenceTimer() > Tframe_abort) {
             /* indicate that an error has occurred during the reception of a frame */
             mstp_port->ReceivedInvalidFrame = true;
 #if PRINT_ENABLED_RECEIVE_ERRORS
             fprintf(stderr,"MSTP: Rx Data: SilenceTimer %d > %d\n",
-                mstp_port->SilenceTimer, Tframe_abort);
+                mstp_port->SilenceTimer(), Tframe_abort);
 #endif
             /* wait for the start of the next frame. */
             mstp_port->receive_state = MSTP_RECEIVE_STATE_IDLE;
@@ -514,7 +514,7 @@ void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
         /* Error */
         else if (mstp_port->ReceiveError == true) {
             mstp_port->ReceiveError = false;
-            mstp_port->SilenceTimer = 0;
+            mstp_port->SilenceTimerReset();
             /* indicate that an error has occurred during the reception of a frame */
             mstp_port->ReceivedInvalidFrame = true;
 #if PRINT_ENABLED_RECEIVE_ERRORS
@@ -577,7 +577,7 @@ void MSTP_Receive_Frame_FSM(volatile struct mstp_port_struct_t *mstp_port)
                 mstp_port->receive_state = MSTP_RECEIVE_STATE_IDLE;
             }
             mstp_port->DataAvailable = false;
-            mstp_port->SilenceTimer = 0;
+            mstp_port->SilenceTimerReset();
         }
         break;
     default:
@@ -631,7 +631,7 @@ bool MSTP_Master_Node_FSM(volatile struct mstp_port_struct_t * mstp_port)
             next_poll_station,
             mstp_port->EventCount,
             mstp_port->TokenCount,
-            mstp_port->SilenceTimer,
+            mstp_port->SilenceTimer(),
             mstptext_master_state(mstp_port->master_state));
     }
 #endif
@@ -654,7 +654,7 @@ bool MSTP_Master_Node_FSM(volatile struct mstp_port_struct_t * mstp_port)
         /* In the IDLE state, the node waits for a frame. */
     case MSTP_MASTER_STATE_IDLE:
         /* LostToken */
-        if (mstp_port->SilenceTimer >= Tno_token) {
+        if (mstp_port->SilenceTimer() >= Tno_token) {
             /* assume that the token has been lost */
             mstp_port->EventCount = 0;  /* Addendum 135-2004d-8 */
             mstp_port->master_state = MSTP_MASTER_STATE_NO_TOKEN;
@@ -673,7 +673,7 @@ bool MSTP_Master_Node_FSM(volatile struct mstp_port_struct_t * mstp_port)
                 mstp_port->DestinationAddress,
                 mstp_port->DataLength,
                 mstp_port->FrameCount,
-                mstp_port->SilenceTimer,
+                mstp_port->SilenceTimer(),
                 mstptext_frame_type(mstp_port->FrameType));
 #endif
             /* destined for me! */
@@ -744,7 +744,7 @@ bool MSTP_Master_Node_FSM(volatile struct mstp_port_struct_t * mstp_port)
             mstp_port->FrameCount = mstp_port->Nmax_info_frames;
             mstp_port->master_state = MSTP_MASTER_STATE_DONE_WITH_TOKEN;
             transition_now = true;
-        } else if (mstp_port->SilenceTimer > Tusage_delay) {
+        } else if (mstp_port->SilenceTimer() > Tusage_delay) {
             /* Don't send it if we are too late in getting out. */
             /* Don't worry.  If we missed our timing deadline, 
                another token will be sent */
@@ -781,7 +781,7 @@ bool MSTP_Master_Node_FSM(volatile struct mstp_port_struct_t * mstp_port)
         /* In the WAIT_FOR_REPLY state, the node waits for  */
         /* a reply from another node. */
     case MSTP_MASTER_STATE_WAIT_FOR_REPLY:
-        if (mstp_port->SilenceTimer >= Treply_timeout) {
+        if (mstp_port->SilenceTimer() >= Treply_timeout) {
             /* ReplyTimeout */
             /* assume that the request has failed */
             mstp_port->FrameCount = mstp_port->Nmax_info_frames;
@@ -917,7 +917,7 @@ bool MSTP_Master_Node_FSM(volatile struct mstp_port_struct_t * mstp_port)
         /* The PASS_TOKEN state listens for a successor to begin using */
         /* the token that this node has just attempted to pass. */
     case MSTP_MASTER_STATE_PASS_TOKEN:
-        if (mstp_port->SilenceTimer <= Tusage_timeout) {
+        if (mstp_port->SilenceTimer() <= Tusage_timeout) {
             if (mstp_port->EventCount > Nmin_octets) {
                 /* SawTokenUser */
                 /* Assume that a frame has been sent by the new token user.  */
@@ -957,13 +957,13 @@ bool MSTP_Master_Node_FSM(volatile struct mstp_port_struct_t * mstp_port)
             }
         }
         break;
-        /* The NO_TOKEN state is entered if mstp_port->SilenceTimer becomes greater  */
+        /* The NO_TOKEN state is entered if mstp_port->SilenceTimer() becomes greater  */
         /* than Tno_token, indicating that there has been no network activity */
         /* for that period of time. The timeout is continued to determine  */
         /* whether or not this node may create a token. */
     case MSTP_MASTER_STATE_NO_TOKEN:
         my_timeout = Tno_token + (Tslot * mstp_port->This_Station);
-        if (mstp_port->SilenceTimer < my_timeout) {
+        if (mstp_port->SilenceTimer() < my_timeout) {
             if (mstp_port->EventCount > Nmin_octets) {
                 /* SawFrame */
                 /* Some other node exists at a lower address.  */
@@ -974,7 +974,7 @@ bool MSTP_Master_Node_FSM(volatile struct mstp_port_struct_t * mstp_port)
         } else {
             ns_timeout =
                 Tno_token + (Tslot * (mstp_port->This_Station + 1));
-            if (mstp_port->SilenceTimer < ns_timeout) {
+            if (mstp_port->SilenceTimer() < ns_timeout) {
                 /* GenerateToken */
                 /* Assume that this node is the lowest numerical address  */
                 /* on the network and is empowered to create a token.  */
@@ -1026,7 +1026,7 @@ bool MSTP_Master_Node_FSM(volatile struct mstp_port_struct_t * mstp_port)
                 transition_now = true;
             }
             mstp_port->ReceivedValidFrame = false;
-        } else if ((mstp_port->SilenceTimer > Tusage_timeout) ||
+        } else if ((mstp_port->SilenceTimer() > Tusage_timeout) ||
             (mstp_port->ReceivedInvalidFrame == true)) {
             if (mstp_port->SoleMaster == true) {
                 /* SoleMaster */
@@ -1084,7 +1084,7 @@ bool MSTP_Master_Node_FSM(volatile struct mstp_port_struct_t * mstp_port)
            see if the next message was that same APDU type
            along with the matching src/dest and invoke ID */
         /* FIXME: we could use 2 queues: one for DER and one for non-DER */
-        if ((mstp_port->SilenceTimer <= Treply_delay) &&
+        if ((mstp_port->SilenceTimer() <= Treply_delay) &&
             mstp_port->TxReady) {
             /* Reply */
             /* If a reply is available from the higher layers  */
@@ -1139,6 +1139,7 @@ bool MSTP_Master_Node_FSM(volatile struct mstp_port_struct_t * mstp_port)
 /* note: Nmax_master assumed to be set (default=127) */
 /* note: InputBuffer and InputBufferSize assumed to be set */
 /* note: OutputBuffer and OutputBufferSize assumed to be set */
+/* note: SilenceTimer and SilenceTimerReset assumed to be set */
 void MSTP_Init(volatile struct mstp_port_struct_t *mstp_port)
 {
     if (mstp_port) {
@@ -1162,7 +1163,7 @@ void MSTP_Init(volatile struct mstp_port_struct_t *mstp_port)
         mstp_port->ReceivedInvalidFrame = false;
         mstp_port->ReceivedValidFrame = false;
         mstp_port->RetryCount = 0;
-        mstp_port->SilenceTimer = 0;
+        mstp_port->SilenceTimerReset();
         mstp_port->SoleMaster = false;
         mstp_port->SourceAddress = 0;
         mstp_port->TokenCount = 0;
@@ -1174,9 +1175,12 @@ void MSTP_Init(volatile struct mstp_port_struct_t *mstp_port)
         mstp_port->InputBufferSize = sizeof(InputBuffer);
         mstp_port->OutputBuffer = &OutputBuffer[0];
         mstp_port->OutputBufferSize = sizeof(OutputBuffer);
-        /* these are adjustable, so you must set these in dlmstp */
+        /* FIXME: these are adjustable, so you must set these in dlmstp */
         mstp_port->Nmax_info_frames = DEFAULT_MAX_INFO_FRAMES;
         mstp_port->Nmax_master = DEFAULT_MAX_MASTER;
+        /* FIXME: point to functions */
+        mstp_port->SilenceTimer = Timer_Silence;
+        mstp_port=>SilenceTimerReset = Timer_Silence_Reset;
 #endif
     }
 }
@@ -1259,6 +1263,16 @@ uint16_t MSTP_Get_Send(
     return 0;
 }
 
+uint16_t SilenceTime = 0;
+static uint16_t Timer_Silence(void)
+{
+    return SilenceTime;
+}
+static void Timer_Silence_Reset(void)
+{
+    SilenceTime = 0;
+}
+
 void testReceiveNodeFSM(Test * pTest)
 {
     volatile struct mstp_port_struct_t mstp_port;       /* port data */
@@ -1269,12 +1283,15 @@ void testReceiveNodeFSM(Test * pTest)
     unsigned len;               /* used for the size of the message packet */
     size_t i;                   /* used to loop through the message bytes */
     uint8_t buffer[MAX_MPDU] = { 0 };
-    uint8_t data[MAX_MPDU - 8 /*header */  - 2 /*CRC*/] = { 0 };
+    uint8_t data[MAX_PDU] = { 0 };
+    uint8_t dummy[8] = {1,2,3,4,5,6,7,8};
 
     mstp_port.InputBuffer = &RxBuffer[0];
     mstp_port.InputBufferSize = sizeof(RxBuffer);
     mstp_port.OutputBuffer = &TxBuffer[0];
     mstp_port.OutputBufferSize = sizeof(TxBuffer);
+    mstp_port.SilenceTimer = Timer_Silence;
+    mstp_port.SilenceTimerReset = Timer_Silence_Reset;
     mstp_port.This_Station = my_mac;
     mstp_port.Nmax_info_frames = 1;
     mstp_port.Nmax_master = 127;
@@ -1283,12 +1300,12 @@ void testReceiveNodeFSM(Test * pTest)
     /* check the receive error during idle */
     mstp_port.receive_state = MSTP_RECEIVE_STATE_IDLE;
     mstp_port.ReceiveError = true;
-    mstp_port.SilenceTimer = 255;
+    SilenceTime = 255;
     mstp_port.EventCount = 0;
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.EventCount == EventCount);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.ReceiveError == false);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_IDLE);
 
@@ -1298,7 +1315,7 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.DataAvailable == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_IDLE);
 
@@ -1308,11 +1325,11 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.DataAvailable == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_PREAMBLE);
     /* force the timeout */
-    mstp_port.SilenceTimer = Tframe_abort + 1;
+    SilenceTime = Tframe_abort + 1;
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_IDLE);
 
@@ -1322,7 +1339,7 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.DataAvailable == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_PREAMBLE);
     /* force the error */
@@ -1330,7 +1347,7 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.ReceiveError == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_IDLE);
 
@@ -1340,7 +1357,7 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.DataAvailable == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_PREAMBLE);
     MSTP_Receive_Frame_FSM(&mstp_port);
@@ -1355,7 +1372,7 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.DataAvailable == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_PREAMBLE);
     /* repeated preamble1 */
@@ -1364,7 +1381,7 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.DataAvailable == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_PREAMBLE);
     /* bad data */
@@ -1373,7 +1390,7 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.ReceiveError == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_IDLE);
 
@@ -1383,7 +1400,7 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.DataAvailable == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_PREAMBLE);
     MSTP_Receive_Frame_FSM(&mstp_port);
@@ -1393,13 +1410,13 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.DataAvailable == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.Index == 0);
     ct_test(pTest, mstp_port.HeaderCRC == 0xFF);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_HEADER);
     /* force the timeout */
-    mstp_port.SilenceTimer = Tframe_abort + 1;
+    SilenceTime = Tframe_abort + 1;
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_IDLE);
     ct_test(pTest, mstp_port.ReceivedInvalidFrame == true);
@@ -1410,7 +1427,7 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.DataAvailable == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_PREAMBLE);
     MSTP_Receive_Frame_FSM(&mstp_port);
@@ -1420,7 +1437,7 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.DataAvailable == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.Index == 0);
     ct_test(pTest, mstp_port.HeaderCRC == 0xFF);
@@ -1430,7 +1447,7 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.ReceiveError == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_IDLE);
 
@@ -1440,7 +1457,7 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.DataAvailable == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_PREAMBLE);
     MSTP_Receive_Frame_FSM(&mstp_port);
@@ -1450,7 +1467,7 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.DataAvailable == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.Index == 0);
     ct_test(pTest, mstp_port.HeaderCRC == 0xFF);
@@ -1469,7 +1486,7 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.DataAvailable == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.Index == 1);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_HEADER);
@@ -1481,7 +1498,7 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.DataAvailable == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.Index == 2);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_HEADER);
@@ -1493,7 +1510,7 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.DataAvailable == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.Index == 3);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_HEADER);
@@ -1505,7 +1522,7 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.DataAvailable == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.Index == 4);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_HEADER);
@@ -1517,7 +1534,7 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.DataAvailable == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.Index == 5);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_HEADER);
@@ -1529,16 +1546,12 @@ void testReceiveNodeFSM(Test * pTest)
     INCREMENT_AND_LIMIT_UINT8(EventCount);
     MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.DataAvailable == false);
-    ct_test(pTest, mstp_port.SilenceTimer == 0);
+    ct_test(pTest, mstp_port.SilenceTimer() == 0);
     ct_test(pTest, mstp_port.EventCount == EventCount);
     ct_test(pTest, mstp_port.Index == 5);
     ct_test(pTest,
-        mstp_port.receive_state == MSTP_RECEIVE_STATE_HEADER_CRC);
+        mstp_port.receive_state == MSTP_RECEIVE_STATE_IDLE);
     ct_test(pTest, mstp_port.HeaderCRC == 0x55);
-    /* NotForUs */
-    MSTP_Receive_Frame_FSM(&mstp_port);
-    ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_IDLE);
-
     /* BadCRC in header check */
     mstp_port.ReceivedInvalidFrame = false;
     mstp_port.ReceivedValidFrame = false;
@@ -1555,12 +1568,9 @@ void testReceiveNodeFSM(Test * pTest)
         INCREMENT_AND_LIMIT_UINT8(EventCount);
         MSTP_Receive_Frame_FSM(&mstp_port);
         ct_test(pTest, mstp_port.DataAvailable == false);
-        ct_test(pTest, mstp_port.SilenceTimer == 0);
+        ct_test(pTest, mstp_port.SilenceTimer() == 0);
         ct_test(pTest, mstp_port.EventCount == EventCount);
     }
-    ct_test(pTest,
-        mstp_port.receive_state == MSTP_RECEIVE_STATE_HEADER_CRC);
-    MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.ReceivedInvalidFrame == true);
     ct_test(pTest, mstp_port.ReceivedValidFrame == false);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_IDLE);
@@ -1579,12 +1589,9 @@ void testReceiveNodeFSM(Test * pTest)
         INCREMENT_AND_LIMIT_UINT8(EventCount);
         MSTP_Receive_Frame_FSM(&mstp_port);
         ct_test(pTest, mstp_port.DataAvailable == false);
-        ct_test(pTest, mstp_port.SilenceTimer == 0);
+        ct_test(pTest, mstp_port.SilenceTimer() == 0);
         ct_test(pTest, mstp_port.EventCount == EventCount);
     }
-    ct_test(pTest,
-        mstp_port.receive_state == MSTP_RECEIVE_STATE_HEADER_CRC);
-    MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.ReceivedInvalidFrame == false);
     ct_test(pTest, mstp_port.ReceivedValidFrame == true);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_IDLE);
@@ -1592,7 +1599,9 @@ void testReceiveNodeFSM(Test * pTest)
     /* FrameTooLong */
     mstp_port.ReceivedInvalidFrame = false;
     mstp_port.ReceivedValidFrame = false;
-    len = MSTP_Create_Frame(buffer, sizeof(buffer), FRAME_TYPE_TOKEN, my_mac,   /* destination */
+    len = MSTP_Create_Frame(buffer, sizeof(buffer),
+        FRAME_TYPE_TOKEN,
+        my_mac,   /* destination */
         my_mac,                 /* source */
         NULL,                   /* data */
         0);                     /* data size */
@@ -1605,12 +1614,9 @@ void testReceiveNodeFSM(Test * pTest)
         INCREMENT_AND_LIMIT_UINT8(EventCount);
         MSTP_Receive_Frame_FSM(&mstp_port);
         ct_test(pTest, mstp_port.DataAvailable == false);
-        ct_test(pTest, mstp_port.SilenceTimer == 0);
+        ct_test(pTest, mstp_port.SilenceTimer() == 0);
         ct_test(pTest, mstp_port.EventCount == EventCount);
     }
-    ct_test(pTest,
-        mstp_port.receive_state == MSTP_RECEIVE_STATE_HEADER_CRC);
-    MSTP_Receive_Frame_FSM(&mstp_port);
     ct_test(pTest, mstp_port.ReceivedInvalidFrame == true);
     ct_test(pTest, mstp_port.ReceivedValidFrame == false);
     ct_test(pTest, mstp_port.receive_state == MSTP_RECEIVE_STATE_IDLE);
@@ -1619,7 +1625,9 @@ void testReceiveNodeFSM(Test * pTest)
     mstp_port.ReceivedInvalidFrame = false;
     mstp_port.ReceivedValidFrame = false;
     memset(data, 0, sizeof(data));
-    len = MSTP_Create_Frame(buffer, sizeof(buffer), FRAME_TYPE_PROPRIETARY_MIN, my_mac, /* destination */
+    len = MSTP_Create_Frame(buffer, sizeof(buffer),
+        FRAME_TYPE_PROPRIETARY_MIN,
+        my_mac, /* destination */
         my_mac,                 /* source */
         data,                   /* data */
         sizeof(data));          /* data size */
@@ -1651,8 +1659,11 @@ void testMasterNodeFSM(Test * pTest)
     MSTP_Port.This_Station = my_mac;
     MSTP_Port.Nmax_info_frames = 1;
     MSTP_Port.Nmax_master = 127;
+    MSTP_Port.SilenceTimer = Timer_Silence;
+    MSTP_Port.SilenceTimerReset = Timer_Silence_Reset;
     MSTP_Init(&MSTP_Port);
     ct_test(pTest, MSTP_Port.master_state == MSTP_MASTER_STATE_INITIALIZE);
+    /* FIXME: write a unit test for the Master Node State Machine */
 
 }
 
diff --git a/bacnet-stack/mstp.h b/bacnet-stack/mstp.h
index 03269bf6..eba8f2f3 100644
--- a/bacnet-stack/mstp.h
+++ b/bacnet-stack/mstp.h
@@ -192,7 +192,10 @@ struct mstp_port_struct_t {
     /* Since the timer resolution is limited and the timer is not necessarily */
     /* synchronized to other machine events, a timer value of N will actually */
     /* denote intervals between N-1 and N */
-    uint16_t SilenceTimer;
+    /* Note: done here as functions - put into timer task or ISR
+       so that you can be atomic on 8 bit microcontrollers */
+    uint16_t (*SilenceTimer)(void);
+    void (*SilenceTimerReset)(void);
 
     /* A timer used to measure and generate Reply Postponed frames.  It is */
     /* incremented by a timer process and is cleared by the Master Node State */
diff --git a/bacnet-stack/ports/at91sam7s/dlmstp.c b/bacnet-stack/ports/at91sam7s/dlmstp.c
index 999af867..b381bdaf 100644
--- a/bacnet-stack/ports/at91sam7s/dlmstp.c
+++ b/bacnet-stack/ports/at91sam7s/dlmstp.c
@@ -33,6 +33,7 @@
 #include "npdu.h"
 /* This file has been customized for use with the AT91SAM7S-EK */
 #include "board.h"
+#include "timer.h"
 
 /* Number of MS/TP Packets Rx/Tx */
 uint16_t MSTP_Packets = 0;
@@ -46,13 +47,6 @@ static volatile struct mstp_port_struct_t MSTP_Port;
 static uint8_t TxBuffer[MAX_MPDU];
 static uint8_t RxBuffer[MAX_MPDU];
 
-#define INCREMENT_AND_LIMIT_UINT16(x) {if (x < 0xFFFF) x++;}
-
-volatile uint16_t *dlmstp_millisecond_timer_address(void)
-{
-    return &(MSTP_Port.SilenceTimer);
-}
-
 void dlmstp_copy_bacnet_address(BACNET_ADDRESS * dest, BACNET_ADDRESS * src)
 {
     int i = 0;
@@ -83,8 +77,10 @@ bool dlmstp_init(char *ifname)
     MSTP_Port.InputBufferSize = sizeof(RxBuffer);
     MSTP_Port.OutputBuffer = &TxBuffer[0];
     MSTP_Port.OutputBufferSize = sizeof(TxBuffer);
+    MSTP_Init.SilenceTimer = Timer_Silence;
+    MSTP_Init.SilenceTimerReset = Timer_Silence_Reset;
     MSTP_Init(&MSTP_Port);
-    
+
     return true;
 }
 
diff --git a/bacnet-stack/ports/at91sam7s/timer.c b/bacnet-stack/ports/at91sam7s/timer.c
index 2ee203d6..b332d3dc 100644
--- a/bacnet-stack/ports/at91sam7s/timer.c
+++ b/bacnet-stack/ports/at91sam7s/timer.c
@@ -45,11 +45,12 @@
 #include "board.h"
 #include "dlmstp.h"
 
-// global variable counts interrupts
+/* global variable counts interrupts */
 volatile unsigned long Timer_Milliseconds;
-volatile uint16_t *pTimer_MSTP_Silence;
+/* MS/TP Silence Timer */
+static volatile uint16_t SilenceTime;
 
-void Timer0_Setup(int milliseconds) {
+static void Timer0_Setup(int milliseconds) {
     //        TC Block Control Register TC_BCR    (read/write)
     //
     //    |------------------------------------------------------------------|------|
@@ -296,7 +297,7 @@ void Timer0_Setup(int milliseconds) {
 //  Modified by Steve Karg
 //    simplified and changed to a millisecond count-up timer
 //  *****************************************************************************
-void Timer0IrqHandler (void) {
+static void Timer0IrqHandler (void) {
 
     volatile AT91PS_TC pTC = AT91C_BASE_TC0; // pointer to timer channel 0 register structure
     unsigned int dummy; // temporary
@@ -305,10 +306,21 @@ void Timer0IrqHandler (void) {
     dummy = pTC->TC_SR;
     // increment the tick count
     Timer_Milliseconds++;
-    if ((*pTimer_MSTP_Silence) < 0xFFFF)
-        (*pTimer_MSTP_Silence)++;
+    if (SilenceTime < 0xFFFF)
+        SilenceTime++;
 }
 
+uint16_t Timer_Silence(void)
+{
+    return SilenceTime;
+}
+
+void Timer_Silence_Reset(void)
+{
+    SilenceTime = 0;
+}
+
+
 //  *****************************************************************************
 //
 //     Timer 0 Initialization
diff --git a/bacnet-stack/ports/at91sam7s/timer.h b/bacnet-stack/ports/at91sam7s/timer.h
new file mode 100644
index 00000000..7a359e68
--- /dev/null
+++ b/bacnet-stack/ports/at91sam7s/timer.h
@@ -0,0 +1,44 @@
+/**************************************************************************
+*
+* Copyright (C) 2007 Steve Karg <skarg@users.sourceforge.net>
+*
+* Permission is hereby granted, free of charge, to any person obtaining
+* a copy of this software and associated documentation files (the
+* "Software"), to deal in the Software without restriction, including
+* without limitation the rights to use, copy, modify, merge, publish,
+* distribute, sublicense, and/or sell copies of the Software, and to
+* permit persons to whom the Software is furnished to do so, subject to
+* the following conditions:
+*
+* The above copyright notice and this permission notice shall be included
+* in all copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*
+*********************************************************************/
+
+#ifndef TIMER_H
+#define TIMER_H
+
+#include <stdint.h>
+
+extern volatile unsigned long Timer_Milliseconds;
+
+#ifdef __cplusplus
+extern "C" {
+#endif                          /* __cplusplus */
+
+    void TimerInit(void);
+    uint16_t Timer_Silence(void);
+    void Timer_Silence_Reset(void);
+
+#ifdef __cplusplus
+}
+#endif                          /* __cplusplus */
+#endif
diff --git a/bacnet-stack/ports/atmega168/main.c b/bacnet-stack/ports/atmega168/main.c
index 6afd295c..008af7b3 100644
--- a/bacnet-stack/ports/atmega168/main.c
+++ b/bacnet-stack/ports/atmega168/main.c
@@ -75,7 +75,7 @@ void init(void)
     RS485_Set_Baud_Rate(38400);
 
     /* Configure Timer0 for millisecond timer */
-    timer_initialize();
+    Timer_Initialize();
 
     /* Enable global interrupts */
     sei();
@@ -86,9 +86,6 @@ void task_milliseconds(void)
     while (Timer_Milliseconds) {
         Timer_Milliseconds--;
         /* add other millisecond timer tasks here */
-#if defined(BACDL_MSTP)
-        dlmstp_millisecond_timer();
-#endif
     }
 }
 
diff --git a/bacnet-stack/ports/atmega168/rs485.c b/bacnet-stack/ports/atmega168/rs485.c
index 23e7ec92..a96ab9a1 100644
--- a/bacnet-stack/ports/atmega168/rs485.c
+++ b/bacnet-stack/ports/atmega168/rs485.c
@@ -128,7 +128,7 @@ void RS485_Send_Frame(
         if (!turnaround_time) {
             turnaround_time = 1;
         }
-        while (mstp_port->SilenceTimer < turnaround_time) {
+        while (mstp_port->SilenceTimer() < turnaround_time) {
             /* do nothing - wait for timer to increment */
         };
     }
@@ -146,7 +146,7 @@ void RS485_Send_Frame(
     }
     /* per MSTP spec */
     if (mstp_port) {
-        mstp_port->SilenceTimer = 0;
+        mstp_port->SilenceTimerReset();
     }
 
     return;
diff --git a/bacnet-stack/ports/atmega168/timer.c b/bacnet-stack/ports/atmega168/timer.c
index d2ce820c..f7b27877 100644
--- a/bacnet-stack/ports/atmega168/timer.c
+++ b/bacnet-stack/ports/atmega168/timer.c
@@ -37,9 +37,11 @@
 #define TIMER_COUNT (0xFF-TIMER_TICKS)
 /* Global variable millisecond timer - used by main.c for timers task */
 volatile uint8_t Timer_Milliseconds = 0;
+/* MS/TP Silence Timer */
+static volatile uint16_t SilenceTime;
 
 /* Configure the Timer */
-void timer_initialize(void)
+void Timer_Initialize(void)
 {
     /* Normal Operation */
     TCCR1A = 0;
@@ -76,4 +78,31 @@ ISR(TIMER0_OVF_vect)
     /* Update the global timer */
     if (Timer_Milliseconds < 0xFF)
        Timer_Milliseconds++;
+    if (SilenceTime < 0xFFFF)
+        SilenceTime++;
+}
+
+/* Public access to the Silence Timer */
+uint16_t Timer_Silence(void)
+{
+    uint16_t timer;
+    uint8_t sreg;
+
+    sreg = SREG;
+    cli();
+    timer = SilenceTime;
+    SREG = sreg;
+
+    return timer;
+}
+
+/* Public reset of the Silence Timer */
+void Timer_Silence_Reset(void)
+{
+    uint8_t sreg;
+
+    sreg = SREG;
+    cli();
+    SilenceTime = 0;
+    SREG = sreg;
 }
diff --git a/bacnet-stack/ports/atmega168/timer.h b/bacnet-stack/ports/atmega168/timer.h
index f49493a2..b5efbcc1 100644
--- a/bacnet-stack/ports/atmega168/timer.h
+++ b/bacnet-stack/ports/atmega168/timer.h
@@ -27,6 +27,16 @@
 
 extern volatile uint8_t Timer_Milliseconds;
 
-void timer_initialize(void);
+#ifdef __cplusplus
+extern "C" {
+#endif                          /* __cplusplus */
+
+void Timer_Initialize(void);
+uint16_t Timer_Silence(void);
+void Timer_Silence_Reset(void);
+
+#ifdef __cplusplus
+}
+#endif                          /* __cplusplus */
 
 #endif
diff --git a/bacnet-stack/ports/linux/dlmstp.c b/bacnet-stack/ports/linux/dlmstp.c
index 5b16309c..fdf1fe5f 100644
--- a/bacnet-stack/ports/linux/dlmstp.c
+++ b/bacnet-stack/ports/linux/dlmstp.c
@@ -58,12 +58,21 @@ volatile struct mstp_port_struct_t MSTP_Port;
 /* buffers needed by mstp port struct */
 static uint8_t TxBuffer[MAX_MPDU];
 static uint8_t RxBuffer[MAX_MPDU];
-
+/* Timer that indicates line silence - and functions */
+static uint16_t SilenceTime;
 #define INCREMENT_AND_LIMIT_UINT16(x) {if (x < 0xFFFF) x++;}
+static uint16_t Timer_Silence(void)
+{
+    return SilenceTime;
+}
+static void Timer_Silence_Reset(void)
+{
+    SilenceTime = 0;
+}
 
 void dlmstp_millisecond_timer(void)
 {
-    INCREMENT_AND_LIMIT_UINT16(MSTP_Port.SilenceTimer);
+    INCREMENT_AND_LIMIT_UINT16(SilenceTime);
 }
 
 static void *dlmstp_milliseconds_task(void *pArg)
@@ -590,6 +599,8 @@ bool dlmstp_init(char *ifname)
     MSTP_Port.InputBufferSize = sizeof(RxBuffer);
     MSTP_Port.OutputBuffer = &TxBuffer[0];
     MSTP_Port.OutputBufferSize = sizeof(TxBuffer);
+    MSTP_Port.SilenceTimer = Timer_Silence;
+    MSTP_Port.SilenceTimerReset = Timer_Silence_Reset;
     MSTP_Init(&MSTP_Port);
 #if 0
     /* FIXME: implement your data storage */
diff --git a/bacnet-stack/ports/linux/rs485.c b/bacnet-stack/ports/linux/rs485.c
index 921b586d..355fb204 100644
--- a/bacnet-stack/ports/linux/rs485.c
+++ b/bacnet-stack/ports/linux/rs485.c
@@ -157,7 +157,7 @@ void RS485_Send_Frame(
             turnaround_time = 2;
         else
             turnaround_time = 1;
-        while (mstp_port->SilenceTimer < turnaround_time) {
+        while (mstp_port->SilenceTimer() < turnaround_time) {
             /* do nothing - wait for timer to increment */
             sched_yield();
         };
@@ -173,7 +173,7 @@ void RS485_Send_Frame(
 
     /* per MSTP spec, sort of */
     if (mstp_port) {
-        mstp_port->SilenceTimer = 0;
+        mstp_port->SilenceTimerReset();
     }
 
     return;
diff --git a/bacnet-stack/ports/win32/dlmstp.c b/bacnet-stack/ports/win32/dlmstp.c
index 221a0c02..5651ecec 100644
--- a/bacnet-stack/ports/win32/dlmstp.c
+++ b/bacnet-stack/ports/win32/dlmstp.c
@@ -53,12 +53,21 @@ volatile struct mstp_port_struct_t MSTP_Port;
 /* buffers needed by mstp port struct */
 static uint8_t TxBuffer[MAX_MPDU];
 static uint8_t RxBuffer[MAX_MPDU];
-
+/* Timer that indicates line silence - and functions */
+static uint16_t SilenceTime;
 #define INCREMENT_AND_LIMIT_UINT16(x) {if (x < 0xFFFF) x++;}
+static uint16_t Timer_Silence(void)
+{
+    return SilenceTime;
+}
+static void Timer_Silence_Reset(void)
+{
+    SilenceTime = 0;
+}
 
 void dlmstp_millisecond_timer(void)
 {
-    INCREMENT_AND_LIMIT_UINT16(MSTP_Port.SilenceTimer);
+    INCREMENT_AND_LIMIT_UINT16(SilenceTime);
 }
 
 void dlmstp_reinit(void)
@@ -435,6 +444,8 @@ bool dlmstp_init(char *ifname)
     MSTP_Port.InputBufferSize = sizeof(RxBuffer);
     MSTP_Port.OutputBuffer = &TxBuffer[0];
     MSTP_Port.OutputBufferSize = sizeof(TxBuffer);
+    MSTP_Init.SilenceTimer = Timer_Silence;
+    MSTP_Init.SilenceTimerReset = Timer_Silence_Reset;
     MSTP_Init(&MSTP_Port);
 #if 0
     uint8_t data;
diff --git a/bacnet-stack/ports/win32/rs485.c b/bacnet-stack/ports/win32/rs485.c
index 15b70da4..0c69801c 100644
--- a/bacnet-stack/ports/win32/rs485.c
+++ b/bacnet-stack/ports/win32/rs485.c
@@ -279,7 +279,6 @@ void RS485_Send_Frame(
 {
     DWORD dwWritten  = 0;
 
-    #if 0
     if (mstp_port) {
         uint32_t baud;
         uint8_t turnaround_time;
@@ -291,16 +290,15 @@ void RS485_Send_Frame(
             turnaround_time = 2;
         else
             turnaround_time = 1;
-        while (mstp_port->SilenceTimer < turnaround_time) {
+        while (mstp_port->SilenceTimer() < turnaround_time) {
             /* do nothing - wait for timer to increment */
         };
     }
-    #endif
     WriteFile(RS485_Handle, buffer, nbytes, &dwWritten, NULL);
 
     /* per MSTP spec, reset SilenceTimer after each byte is sent */
     if (mstp_port) {
-        mstp_port->SilenceTimer = 0;
+        mstp_port->SilenceTimerReset();
     }
 
     return;
diff --git a/bacnet-stack/version.c b/bacnet-stack/version.c
index b7c12920..14faeb53 100644
--- a/bacnet-stack/version.c
+++ b/bacnet-stack/version.c
@@ -33,4 +33,4 @@
 ####COPYRIGHTEND####*/
 #include "version.h"
 
-char *BACnet_Version = "0.3.4";
+char *BACnet_Version = BACNET_VERSION_TEXT;
diff --git a/bacnet-stack/version.h b/bacnet-stack/version.h
index 5b828831..821fd23c 100644
--- a/bacnet-stack/version.h
+++ b/bacnet-stack/version.h
@@ -38,7 +38,9 @@
 #ifndef BACNET_VERSION
 #define BACNET_VERSION(x,y,z) (((x)<<16)+((y)<<8)+(z))
 #endif
-#define BACNET_VERSION_CODE BACNET_VERSION(0,3,4)
+
+#define BACNET_VERSION_TEXT "0.3.5"
+#define BACNET_VERSION_CODE BACNET_VERSION(0,3,5)
 #define BACNET_VERSION_MAJOR ((BACNET_VERSION_CODE>>16)&0xFF)
 #define BACNET_VERSION_MINOR ((BACNET_VERSION_CODE>>8)&0xFF)
 #define BACNET_VERSION_MAINTENANCE (BACNET_VERSION_CODE&0xFF)