Modbus RTU over TCP report error , but modbus poll works fine

Ignition
1

I have 16 power meters connect with 485 then to a serial port .
And I am trying to read the Current value.
When I test with modbus poll, it works well, no error.
But when test with Ignition, there is always error and connection bad.
And some device can't get the value.

Here's my Ignition device setup .
Span gap is unchecked.

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image1060×887 26.1 KB

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image1261×812 35.2 KB

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image1363×886 47.2 KB

Here's error when I am trying to read the value with quick client.

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image1370×819 64.9 KB

Below is screenshot I test with Modbus poll.

All values read well, and no errors.

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image1514×968 123 KB

And there are errors generated in my gateway log every seconds.

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By the way, I have disconnected modbus poll when I test Ignition to make sure there is only one modbus master to read the device.
And as display in the screenshot, I only read 1 register address for each power meter.
So I assume max holding register per request is not a issue either.

And I am using latest version 8.1.43 .
And this is not my first time to use this serial port , but other is in Ignition 8.1.39.
Not sure if this is related, but I DO see there is bug in 8.1.42 release notes regarding Mobus , indicate that single modbus address can't be created.

2

Disable the reconnect after consecutive timeout setting and then get a wireshark capture.

3

If these are input registers at address 3, shouldn't your OPC item path be something like:

ns=1;s=[ACC_250T_1_POWER1]1.IR3
ns=1;s=[ACC_250T_1_POWER1]2.IR3
ns=1;s=[ACC_250T_1_POWER1]3.IR3
ns=1;s=[ACC_250T_1_POWER1]4.IR3
.
.
.
ns=1;s=[ACC_250T_1_POWER1]15.IR3
ns=1;s=[ACC_250T_1_POWER1]16.IR3