How can I use BusTools/1553 API to set the Transmit Channel for a BC message?

Setting the transmit Channel for a BC message is done on a message-by-message basis when you setup the BC message. The following code example shows how this is done. The default channel is A, so if you do not select channel B when setting up the BC message all messages go out on channel A.

   messno = 0;
   memset((char*)&bcmessage,0,sizeof(bcmessage));    
   bcmessage.messno = messno;
   bcmessage.messno_next = (BT_U16BIT)(messno + 1);
   bcmessage.control = BC_CONTROL_MESSAGE;        // show as a message
   bcmessage.control |= BC_CONTROL_BUFFERA;       // use buffer A

   //Use this line for send message on channel A
   bcmessage.control |= BC_CONTROL_CHANNELA;   // Transmit on Channel A
   //Use this line for send message on channel B
   bcmessage.control |= BC_CONTROL_CHANNELB;   // Transmit on Channel B

   bcmessage.control |= BC_CONTROL_INTERRUPT;
   bcmessage.control |= BC_CONTROL_MFRAME_BEG;
   bcmessage.mess_command1.rtaddr   = 2;
   bcmessage.mess_command1.subaddr  = 2;
   bcmessage.mess_command1.wcount   = 2;
   bcmessage.mess_command1.tran_rec = 0;
   bcmessage.errorid = 0;     // Default error injection buffer (no errors)
   bcmessage.gap_time = 800;    // 8 microsecond inter-message gap.
   bcmessage.data[0][0] = 1;
   bcmessage.data[0][1] = 1;

   status = BusTools_BC_MessageWrite(cardnum,messno,&bcmessage);
   printf("BusTools_BC_MessageWrite status = %d\n"