Modbus communication interruptions with a Schneider TSX 3722 PLC

Ignition
1

Every so often, the tags turn red and then return to black shortly afterward. This happens intermittently, but quite frequently.

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GATEWAY Ignition 8.1.53 (b2026032414)

The communications in the Gateway are configured as MODBUS RTU.
Serial Port.

The Tag Group is configured as follows:

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The PLC is a Schneider TSX 3722, communicating through a PCMCIA RS232 MP card.

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The connection to the PLC is made through a selector switch that switches the communications between the old SCADA system and the new Ignition system.

We tested connecting the cable directly to the new SCADA system, bypassing the selector switch, to rule out any issues with the selector switch. However, the problem still occurs.

Any help or suggestions on how to troubleshoot this issue would be greatly appreciated. Thanks in advance!

Best regards,
Manuel

2

The communications in the Gateway are configured as MODBUS RTU.
Serial Port:

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3

Is the driver showing an overload % in the status page?
This is pretty typical of a system that's not quite fast enough on the wire speed for the amount of tags and rate and eventually times out, then starts responding again when the requests get cancelled.