Troubles with ModbusTCP communication

Hi everybody!

We're using Citect 2016 update 38, if i'm not wrong it is the last update for this version.

We have many PLCs already using ModbusTCP without any issues.

Not long ago we added a new PLC. But Citect has never been able to establish a communication. We left Wireshark running on the backgorund and we discovered that Citect sends only one request (which is responded by the device succesfully) and nothing else happens. No other frame is sent from Citect to the PLC. After 100seconds the PLC closes the TCP connection as it doesn't receive any further package from Citect.

After running this test, we created a new empty project with only this PLC and just one variable (the same configuration). We don't understand why but this time the communication works perfectly.

We have already tried to delete the IODevice in the original project and add it again but we get the same results. Besides I think there is not parameter configuring the protocol or port used with this plc in the "config.ini"

Any ideas???

Thanks in advance

Bas over 3 years ago

Can you check if all I/O Devices are configured with their own Port?
Did you install the latest TCPIP-driver from the driver web?
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Iván over 3 years ago

Regarding your first question, I think the answer is yes, nevertheless I'll have another look to make sure.
I'm not really familiar with the driver web, could you give me some insight about it?? Thank you very much
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Bas over 3 years ago

On the aveva support website you can just search for TCPIP. If you have a valid Customer First contract you can download the driver.
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Olivier over 3 years ago

Another config change you could try, is to create a new IOServer to host this new IODevice. Maybe you have reached some limits for number of devices on IOServer?
Also see if Windows event viewer reports any errors (e.g. exhausted TCPIP connects).
As Bas stated, good to download and use latest Modnet driver (requires valid support agreement):
https://softwaresupportsp.aveva.com/#/connectivityhub
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Mark over 3 years ago

Check that the iodevice has a unique iodevice number. If it shares it with another device then Citect will treat it as a redundant pair and only poll it very infrequently just to check it's there.
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