MSTP on Linux appears to be function for the server demo, but dlmstp needs to be rewritten to use posix queues or sockets, and multiple threads for the state machines.

bacnet-stack/demo/server/main.c

@@ -115,6 +115,11 @@ int main(int argc, char *argv[])
     if (argc > 3) {
         dlmstp_set_mac_address(strtol(argv[1], NULL, 0));
     }
+#if 0
+    RS485_Set_Baud_Rate(38400);
+    dlmstp_set_max_info_frames(DEFAULT_MAX_INFO_FRAMES);
+    dlmstp_set_max_master(DEFAULT_MAX_MASTER);
+#endif
 #endif
     printf("BACnet Server Demo\n"
         "BACnet Device ID: %u\r\n",

bacnet-stack/ports/linux/dlmstp.c

@@ -99,11 +99,13 @@ int dlmstp_send_pdu(BACNET_ADDRESS * dest,      /* destination address */
     BACNET_ADDRESS src;
 
     if (MSTP_Port.TxReady == false) {
-        if (npdu_data->data_expecting_reply)
-            MSTP_Port.TxFrameType = FRAME_TYPE_BACNET_DATA_EXPECTING_REPLY;
-        else
+        if (npdu_data->data_expecting_reply) {
+            MSTP_Port.TxFrameType =
+                FRAME_TYPE_BACNET_DATA_EXPECTING_REPLY;
+        } else {
             MSTP_Port.TxFrameType =
                 FRAME_TYPE_BACNET_DATA_NOT_EXPECTING_REPLY;
+        }
 
         /* load destination MAC address */
         if (dest && dest->mac_len == 1) {
@@ -128,39 +130,6 @@ int dlmstp_send_pdu(BACNET_ADDRESS * dest,      /* destination address */
     return bytes_sent;
 }
 
-static void *dlmstp_receive_fsm_task(void *pArg)
-{
-    uint8_t bytes_remaining;
-    bool received_frame;
-
-    for (;;) {
-        /* only do receive state machine while we don't have a frame */
-        if ((MSTP_Port.ReceivedValidFrame == false) &&
-            (MSTP_Port.ReceivedInvalidFrame == false)) {
-            do {
-                bytes_remaining = RS485_Check_UART_Data(&MSTP_Port);
-                MSTP_Receive_Frame_FSM(&MSTP_Port);
-                received_frame = MSTP_Port.ReceivedValidFrame ||
-                    MSTP_Port.ReceivedInvalidFrame;
-                if (received_frame)
-                    break;
-            } while (bytes_remaining);
-        }
-    }
-}
-
-static void *dlmstp_master_fsm_task(void *pArg)
-{
-    for (;;) {
-        /* only do master state machine while rx is idle */
-        if (MSTP_Port.receive_state == MSTP_RECEIVE_STATE_IDLE) {
-            while (MSTP_Master_Node_FSM(&MSTP_Port)) {
-                sched_yield();
-            }
-        }
-    }
-}
-
 /* copy the packet if one is received.
    Return the length of the packet */
 uint16_t dlmstp_receive(
@@ -170,6 +139,26 @@ uint16_t dlmstp_receive(
     unsigned timeout) /* milliseconds to wait for a packet */
 {
     uint16_t len = 0;
+    bool received_frame;
+
+    /* only do receive state machine while we don't have a frame */
+    if ((MSTP_Port.ReceivedValidFrame == false) &&
+        (MSTP_Port.ReceivedInvalidFrame == false)) {
+        do {
+            RS485_Check_UART_Data(&MSTP_Port);
+            MSTP_Receive_Frame_FSM(&MSTP_Port);
+            received_frame = MSTP_Port.ReceivedValidFrame ||
+                MSTP_Port.ReceivedInvalidFrame;
+            if (received_frame)
+                break;
+        } while (MSTP_Port.DataAvailable);
+    }
+    /* only do master state machine while rx is idle */
+    if (MSTP_Port.receive_state == MSTP_RECEIVE_STATE_IDLE) {
+        while (MSTP_Master_Node_FSM(&MSTP_Port)) {
+            sched_yield();
+        }
+    }
     /* see if there is a packet available, and a place
         to put the reply (if necessary) and process it */
     if (Receive_Buffer.ready && !MSTP_Port.TxReady) {
@@ -362,8 +351,6 @@ bool dlmstp_init(char *ifname)
 
     /* start our MilliSec task */
     rc = pthread_create(&hThread, NULL, dlmstp_milliseconds_task, NULL);
-    rc = pthread_create(&hThread, NULL, dlmstp_receive_fsm_task, NULL);
-    rc = pthread_create(&hThread, NULL, dlmstp_master_fsm_task, NULL);
 
     return 1;
 }
@@ -371,33 +358,27 @@ bool dlmstp_init(char *ifname)
 #ifdef TEST_DLMSTP
 #include <stdio.h>
 
-void npdu_handler(
-    BACNET_ADDRESS * src,     /* source address */
-    uint8_t * pdu,          /* PDU data */
-    uint16_t pdu_len)      /* length PDU  */
-{
-    (void)src;
-    (void)pdu;
-    (void)pdu_len;
-    fprintf(stderr, "NPDU: received PDU!\n");
-}
+static char *Network_Interface = NULL;
 
 int main(int argc, char *argv[])
 {
     struct timespec timeOut,remains;
+    uint16_t bytes_received = 0;
+    BACNET_ADDRESS src; /* source address */
+    uint8_t pdu[MAX_APDU]; /* PDU data */
 
     timeOut.tv_sec = 1;
     timeOut.tv_nsec = 0; /* 1 millisecond */
 
     /* argv has the "/dev/ttyS0" or some other device */
     if (argc > 1) {
-        RS485_Set_Interface(argv[1]);
+        Network_Interface = argv[1];
     }
     RS485_Set_Baud_Rate(38400);
     dlmstp_set_mac_address(0x05);
     dlmstp_set_max_info_frames(DEFAULT_MAX_INFO_FRAMES);
     dlmstp_set_max_master(DEFAULT_MAX_MASTER);
-    dlmstp_init();
+    dlmstp_init(Network_Interface);
     /* forever task */
     for (;;) {
 #if 0
@@ -407,10 +388,14 @@ int main(int argc, char *argv[])
             MSTP_Port.SourceAddress,
             MSTP_Port.This_Station,
             NULL, 0);
-#endif
         nanosleep(&timeOut, &remains);
+#endif
+        bytes_received =
+            dlmstp_receive(&src, &pdu[0], sizeof(pdu), 0);
+        if (bytes_received) {
+            fprintf(stderr,"Received NPDU!\n");
+        }
     }
-
     return 0;
 }
 #endif

bacnet-stack/ports/linux/rs485.c

@@ -224,7 +224,7 @@ void RS485_Initialize(void)
         perror(RS485_Port_Name);
         exit(-1);
     }
-#if 0
+#if 1
     /* non blocking for the read */
     fcntl(RS485_Handle, F_SETFL, FNDELAY);
 #else