Problem Polling Modbus Data Range (42497 to 42601)

Ignition
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1

Need help for an issue when polling real time modbus data from a IP device through the Ignition modbus OPC driver. Modbus data is split into 2 holding register ranges:

Range 1 -772 to 1800
These are either integer or float values updating real-time in Ignition successfully. These are accessed in the standard way as any other modbus tags (HRUS772 TO HRUS1800).

Range 2 – 42497 to 42601
These are only integer values and do not update real-time in Ignition. Trying to access these tags, same way as above (HRUS42497 TO HRUS42601)

These values correctly update on a forced modbus read request. For e.g when the address is changed and the restored back to original.

Working around TagGroups and Advanced properties have not yielded any results.

Appreciate help if anybody has come across any such issue and has a solution.

2

You should capture packets showing the communication for a couple minutes while you exercise these subscriptions. (I suspect the device is responsible.)

Also share the brand and model number of the device, and perhaps a link to the user manual.

3

Thanks for the reply.

Cannot doubt the device as I tried reading the range 2 registers through a modbus scanner, which did a good job of updating values in real time.

4

Then a packet capture showing what Ignition is doing versus what that modbus scanner is doing would highlight what mistake is being made in Ignition.

Share more about your tag groups and OPC Item Paths for the affected tags. If using the address mapper (you shouldn't), try replacing your tags' OPC Item Paths with manually addressed items.