Hello,
I have a program that uses 2 V430 to pass data and commands to each other. We will call them Unit A and Unit B.
Unit A will do a MODBUS data table read on Unit B. It reads 50 bytes from address 0 on Unit B and writes them to address 0 on Unit A. After this has completed, I set a write bit and then it performs the data table write
Unit A will do a MODBUS data table write from address 600 on Unit A and write it to Address 600 on Unit B. about 50 bytes. Once the write is complete, it sets the read bit and then the cycle repeats endlessly.
This process happens all the while the unit is powered up and the PLC is not in stop mode.
When my process runs, I will set bits and values and write them to the data table that is being sent to unit B signaling it to start. The process seems to work most of the time. However, from time to time, I will see the data table that is being written to unit B will have garbage data randomly popping up and being tossed all around the table. If I disable the MODBUS read/write section, the data table stops the erratic behavior. Once enabled again, the erratic behavior continues.
If I power cycle the unit, the issue seems to go away.
Lets say my function in progress bit for this particular MODBUS is bit 1. If I am writing from unit A to unit B and while the MODBUS function is taking place, a write to that data table takes place. Will that cause this behavior?
I have tried slowing down the sends and receives but that does not seem to help.
When this has an the issue present, the read table does not seem to read properly either. My status returns from the function are 0.
Thoughts?