DCS Yokogawa Communication Issue

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Thread Starter

Zarar

We encountered a problem with Yokogawa DCS. We have two Data Concentrators (Modbus/TCP Slave) communicating with Yokogawa DCS ALE111 card. The DCS master is configured to poll from both Data Concentrators and to keep the redundancy. DCS master is reading and writing (multiple write)on Data Concentrator which is connected with different relays connected in serial loops.

ISSUE: What is observed that DCS sends a command 32bits to be written on Data Concentrator and it works fine for some time but afterwards the command is not getting executed. Once the ALE card is refreshed or reloaded, it starts working fine for some time but end up with the same problem again.

POSSIBLE ROOT CAUSE:

1- the FCS cards are keep swapping from one link to the other because some points from Data Concentrator are not healthy(Some relays are off) and due to that the cards keep swapping. We thought that there might be a possibility that the command gets discarded because of frequent swapping.

2- The ALE111 card is working on Half-duplex where as the Data Concentrator is working on Full-duplex communication mode but has Auto Negotiation enabled.

Is there anyone who has encountered somewhat similar issue or have any idea on DCS settings to make it work?
 
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Elbert van der Bijl

this behavior is by design and it will not occur when the Modbus slave is correctly responding to the DCS Modbus requests.

There are also work arounds but for that you should contact your nearest Yokogawa office.

You can also drop me an e-mail at [email protected]
and I can provide you with all the details.

Best regards,
Elbert
 
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