diff --git a/bacnet-stack/demo/dcc/main.c b/bacnet-stack/demo/dcc/main.c
index 7398c345..257b26f3 100644
--- a/bacnet-stack/demo/dcc/main.c
+++ b/bacnet-stack/demo/dcc/main.c
@@ -259,12 +259,19 @@ int main(int argc, char *argv[])
                     Communication_Password);
             } else if (tsm_invoke_id_free(invoke_id))
                 break;
+            else if (tsm_invoke_id_failed(invoke_id))
+            {
+              fprintf(stderr, "\rError: TSM Timeout!\r\n");
+              tsm_free_invoke_id(invoke_id);
+              /* try again or abort? */
+              break;
+            }
         } else {
             /* increment timer - exit if timed out */
             elapsed_seconds += (current_seconds - last_seconds);
             if (elapsed_seconds > timeout_seconds)
             {
-                printf("\rError: APDU Timeout!");
+                printf("\rError: APDU Timeout!\r\n");
                 break;
             }
         }
diff --git a/bacnet-stack/demo/object/ai.c b/bacnet-stack/demo/object/ai.c
index c37c47f3..de6b6b8e 100644
--- a/bacnet-stack/demo/object/ai.c
+++ b/bacnet-stack/demo/object/ai.c
@@ -121,7 +121,13 @@ int Analog_Input_Encode_Property_APDU(uint8_t * apdu,
     case PROP_UNITS:
         apdu_len = encode_tagged_enumerated(&apdu[0], UNITS_PERCENT);
         break;
-        /* test case for signed encoding and decoding negative value correctly */
+    case 9997:
+        apdu_len = encode_tagged_real(&apdu[0], 90.510);
+        break;
+    case 9998:
+        apdu_len = encode_tagged_unsigned(&apdu[0], 90);
+        break;
+        /* test case for signed encoding-decoding negative value correctly */
     case 9999:
         apdu_len = encode_tagged_signed(&apdu[0], -200);
         break;
diff --git a/bacnet-stack/demo/readfile/readfile.c b/bacnet-stack/demo/readfile/readfile.c
index 8519f145..3264d59a 100644
--- a/bacnet-stack/demo/readfile/readfile.c
+++ b/bacnet-stack/demo/readfile/readfile.c
@@ -286,12 +286,19 @@ int main(int argc, char *argv[])
                     requestedOctetCount);
                 Current_Invoke_ID = invoke_id;
             }
+            else if (tsm_invoke_id_failed(invoke_id))
+            {
+              fprintf(stderr, "\rError: TSM Timeout!\r\n");
+              tsm_free_invoke_id(invoke_id);
+              /* try again or abort? */
+              break;
+            }
         } else {
             /* increment timer - exit if timed out */
             elapsed_seconds += (current_seconds - last_seconds);
             if (elapsed_seconds > timeout_seconds)
             {
-                printf("\rError: APDU Timeout!");
+                fprintf(stderr, "\rError: APDU Timeout!\r\n");
                 break;
             }
         }
diff --git a/bacnet-stack/demo/readprop/readprop.c b/bacnet-stack/demo/readprop/readprop.c
index 589cfa92..37578e04 100644
--- a/bacnet-stack/demo/readprop/readprop.c
+++ b/bacnet-stack/demo/readprop/readprop.c
@@ -226,12 +226,19 @@ int main(int argc, char *argv[])
                     Target_Object_Index);
             } else if (tsm_invoke_id_free(invoke_id))
                 break;
+            else if (tsm_invoke_id_failed(invoke_id))
+            {
+                fprintf(stderr, "\rError: TSM Timeout!\r\n");
+                tsm_free_invoke_id(invoke_id);
+                /* try again or abort? */
+                break;
+            }
         } else {
             /* increment timer - exit if timed out */
             elapsed_seconds += (current_seconds - last_seconds);
             if (elapsed_seconds > timeout_seconds)
             {
-                printf("\rError: APDU Timeout!");
+                printf("\rError: APDU Timeout!\r\n");
                 break;
             }
         }
diff --git a/bacnet-stack/demo/reinit/main.c b/bacnet-stack/demo/reinit/main.c
index da05ac10..843ef052 100644
--- a/bacnet-stack/demo/reinit/main.c
+++ b/bacnet-stack/demo/reinit/main.c
@@ -245,11 +245,21 @@ int main(int argc, char *argv[])
                     Reinitialize_Password);
             } else if (tsm_invoke_id_free(invoke_id))
                 break;
+            else if (tsm_invoke_id_failed(invoke_id))
+            {
+              fprintf(stderr, "\rError: TSM Timeout!\r\n");
+              tsm_free_invoke_id(invoke_id);
+              /* try again or abort? */
+              break;
+            }
         } else {
             /* increment timer - exit if timed out */
             elapsed_seconds += (current_seconds - last_seconds);
             if (elapsed_seconds > timeout_seconds)
+            {
+                fprintf(stderr, "\rError: APDU Timeout!\r\n");
                 break;
+            }
         }
         /* keep track of time for next check */
         last_seconds = current_seconds;
diff --git a/bacnet-stack/demo/writefile/writefile.c b/bacnet-stack/demo/writefile/writefile.c
index 30f6b505..ca6205e7 100644
--- a/bacnet-stack/demo/writefile/writefile.c
+++ b/bacnet-stack/demo/writefile/writefile.c
@@ -264,12 +264,19 @@ int main(int argc, char *argv[])
                     &fileData);
                 Current_Invoke_ID = invoke_id;
             }
+            else if (tsm_invoke_id_failed(invoke_id))
+            {
+              fprintf(stderr, "\rError: TSM Timeout!\r\n");
+              tsm_free_invoke_id(invoke_id);
+              /* try again or abort? */
+              break;
+            }
         } else {
             /* increment timer - exit if timed out */
             elapsed_seconds += (current_seconds - last_seconds);
             if (elapsed_seconds > timeout_seconds)
             {
-                printf("\rError: APDU Timeout!");
+                fprintf(stderr, "\rError: APDU Timeout!\r\n");
                 break;
             }
         }
diff --git a/bacnet-stack/demo/writeprop/writeprop.c b/bacnet-stack/demo/writeprop/writeprop.c
index 88eceba1..203cb839 100644
--- a/bacnet-stack/demo/writeprop/writeprop.c
+++ b/bacnet-stack/demo/writeprop/writeprop.c
@@ -323,12 +323,19 @@ int main(int argc, char *argv[])
                     Target_Object_Property_Index);
             } else if (tsm_invoke_id_free(invoke_id))
                 break;
+            else if (tsm_invoke_id_failed(invoke_id))
+            {
+                fprintf(stderr, "\rError: TSM Timeout!\r\n");
+                tsm_free_invoke_id(invoke_id);
+                /* try again or abort? */
+                break;
+            }
         } else {
             /* increment timer - exit if timed out */
             elapsed_seconds += (current_seconds - last_seconds);
             if (elapsed_seconds > timeout_seconds)
             {
-                printf("\rError: APDU Timeout!");
+                printf("\rError: APDU Timeout!\r\n");
                 break;
             }
         }
diff --git a/bacnet-stack/tsm.c b/bacnet-stack/tsm.c
index 7e04a227..cd99aada 100644
--- a/bacnet-stack/tsm.c
+++ b/bacnet-stack/tsm.c
@@ -237,7 +237,9 @@ void tsm_timer_milliseconds(uint16_t milliseconds)
                         &TSM_List[i].npdu_data,
                         &TSM_List[i].apdu[0], TSM_List[i].apdu_len);
                 } else {
-                    TSM_List[i].InvokeID = 0;
+                    /* note: the invoke id has not been cleared yet
+                    and this indicates a failed message:
+                    IDLE and a valid invoke id */
                     TSM_List[i].state = TSM_STATE_IDLE;
                 }
             }
@@ -269,6 +271,25 @@ bool tsm_invoke_id_free(uint8_t invokeID)
     return status;
 }
 
+/* see if the invoke ID has failed get a confirmation */
+bool tsm_invoke_id_failed(uint8_t invokeID)
+{
+  bool status = false;
+  uint8_t index;
+
+  index = tsm_find_invokeID_index(invokeID);
+  if (index < MAX_TSM_TRANSACTIONS)
+  {
+      /* a valid invoke ID and the state is IDLE is a
+         message that failed to confirm */
+      if (TSM_List[index].state == TSM_STATE_IDLE)
+          status = true;
+  }
+
+  return status;
+}
+
+
 #ifdef TEST
 #include <assert.h>
 #include <string.h>
diff --git a/bacnet-stack/tsm.h b/bacnet-stack/tsm.h
index 4b7ce5b5..3b3a4f62 100644
--- a/bacnet-stack/tsm.h
+++ b/bacnet-stack/tsm.h
@@ -109,7 +109,8 @@ extern "C" {
         uint8_t * apdu, uint16_t * apdu_len);
 
     bool tsm_invoke_id_free(uint8_t invokeID);
-
+    bool tsm_invoke_id_failed(uint8_t invokeID);
+    
 #ifdef __cplusplus
 }
 #endif                          /* __cplusplus */