Index: firmware/App/Services/SystemCommMessages.c
===================================================================
diff -u -r4eab0a5086a5fddeea6cbdf3f79ce1067851b4be -r6fc5708ce7e0c87a3447921b4a939e3a00e64cbd
--- firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 4eab0a5086a5fddeea6cbdf3f79ce1067851b4be)
+++ firmware/App/Services/SystemCommMessages.c	(.../SystemCommMessages.c)	(revision 6fc5708ce7e0c87a3447921b4a939e3a00e64cbd)
@@ -8,7 +8,7 @@
 * @file    SystemCommMessages.c
 *
 * @author  (last)      Dara Navaei
-* @date    (last)      03-Feb-2023
+* @date    (last)      15-Feb-2023
 *
 * @author  (original)  Dara Navaei
 * @date    (original)  05-Nov-2019
@@ -501,7 +501,7 @@
     }
 
     // serialize the message (w/ sync, CRC, and appropriate CAN padding) and add serialized message data to appropriate comm buffer
-    serializeMessage( msg, COMM_BUFFER_OUT_CAN_DG_BROADCAST, ACK_NOT_REQUIRED );
+    serializeMessage( msg, COMM_BUFFER_OUT_CAN_DG_BROADCAST, ACK_REQUIRED );
 }
 
 /*********************************************************************//**
@@ -4390,7 +4390,8 @@
     BOOL result = FALSE;
 
     // verify payload length
-    if ( sizeof( U32 ) == message->hdr.payloadLen )
+    if ( ( sizeof( U32 ) == message->hdr.payloadLen ) &&
+         ( ( DG_MODE_STAN == getCurrentOperationMode() ) || ( DG_MODE_SOLO == getCurrentOperationMode() ) ) )
     {
         NELSON_SUPPORT_T nelson;
 
@@ -4411,11 +4412,6 @@
                 requestNewOperationMode( DG_MODE_HEAT );
                 break;
 
-            case NELSON_POS_CONTROL_CHEM_DISINFECT:
-                setChemNelsonSupportMode( nelson );
-                requestNewOperationMode( DG_MODE_CHEM );
-                break;
-
             case NELSON_POS_CONTROL_HEAT_DISINFECT:
                 setHeatNelsonSupportMode( nelson );
                 requestNewOperationMode( DG_MODE_HEAT );