We have a Modbus Plus Network linking 12 Quantum 140 CPU 213 04 Processors together.

Each Quantum 140 CPU 213 04 Processor controls a Diesel Genset(12 altogether).

The 12 Quantum 140 CPU 213 04 Processors transfer data to and from each other using Peer Cop Specific Input and Outputs.

The token rotation time for the Modbus Plus Network is 55ms.

The average PLC scan time for each processor is around 240ms.

I want to replace one of the 12 Quantum 140 CPU 213 04 Processors with a faster, newer Quantum Processor, the 140 CPU 534 14A.

With Quantum 140 CPU 534 14A Processor, the PLC scan time is drastically reduced to 18ms for the same program that the older processors were running.

I am slightly concerned though that if I put in the new Quantum 140 CPU 534 14A Processor into the current Modbus Plus with the other slower Quantum 140 CPU 213 04 Processors, it will be too fast for them, with regards to Data Exchange between processors, specifically, Peer Cop Data Transfer.

Thus, I will have a fast processor doing 18ms per scan communicating with 11 other slower processors doing 240ms per scan.

I am thinking the new processor could clog up traffic on the Modbus Plus Network.

Could someone please clarify whether my fears are justified or not?

Any advice would be welcome.

Thanks

 

Modbus plus is a token passing network protocol which operates at 1MB/s which means even low end devices (113CPU) have the potential to read/send alot of data between nodes. All nodes read data on the network but only processes packets that specifies it's node address as the receiving node. Each node has an opportunity to take the token and broadcast data packets.

I manage a network with 15+ Modbus plus nodes ranging from CPU113 to CPU534 to third party nodes; the network is stable, fast and reliable.