I need to establish communication with several MFCs using serial communication (i.e. RS232). Each device has its own address and it is connected to a hub and the hub is connected to the PLC via RS232 cable. To communicate with a device, a trasmitted "command" string begins with the address of the device and each received string also starts with the address of the device. I have no problem using instructions such as AWA and RDL to Tx/Rx to one device, however, my program falls out of sync. when try to communicate to more than one device. I believe the culprit is the RDL or Read instructions that required more than one scan to completely read the buffer.
I was wondering if anyone out there has developed similar PLC software and if they ran into similar situation and how they resolved it.
Thank you.
I was wondering if anyone out there has developed similar PLC software and if they ran into similar situation and how they resolved it.
Thank you.