Comparison of communication latency between Speedgoat real time machine and Matlab host computer to field industrial device via Modbus TCP

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The purpose of the work is to determine the minimum stable latency using the Modbus TCP protocol for further use in real time.

 

For comparison, we used two options:

• Option 1: Speedgoat real-time machine with Speedgoat IO753 (Modbus TCP Master) to a field industrial device SR-M4

• Option 2: host computer with Matlab to a field industrial device SR-M4 (Modbus TCP controlled by Matlab client)

 

The SR-M4 was used as a field industrial device in Server mode. SR-M4 is a device for measurement 16 analog and 16 diskret channels with measurement sample time to 50 𝞵s. This device can answer to Modbus TCP with the same sample time as measurement.

 

Results

• Option 1:   Latency 1 ms (with Speedgoat real-time machine).

• Option 2:   Latency 35 ms (with Matlab host computer).

 

If you need less industrial latency you should use EtherCAT protocol. It can achieve ten times lower latency.