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by

FW ver.: RUT9XX_R_00.06.05.1

I have two questions about Modbus TCP support:
1. Why in Modbus TCP, RUT955 returns an error when the Transaction ID field is greater than 127 in the query? The Modbus TCP documentation says that this field is 2 bytes long, i.e. not 127 but 65535 is the maximum number. Is there a chance in the next release of the company to fix this incompatibility with the protocol?
2. In the current firmware version, the Modbus query for the voltage at the analog input, register number 141, always returns the value 0. Will the next firmware version allow you to correctly read the voltage value under register number 141
When can you expect the release of a revised firmware version?

    

1 Answer

0 votes
by anonymous
Hello,

Our engineers are already informed about the Analog input value always showing 0, so it will be fixed in future updates.

Regarding the register address, have you tried using different Modbus monitoring apps?
by

Thank you for answering the second question, while the first question is still unanswered. We cannot implement this router productionly before solving the problems in both questions.

 Yes, I did the tests using programs:

1. Modbus Master

2. Radzio Modbus Master Simulator

3. qModMaster

4. and our production SCADA system

each time the value read under register 141 was 0.

by anonymous
Please tell me more about the first question.

Is it that none of the functions which register address is higher than 127 work for you?
by

The problem is wrong router responses when the router query packet has a Transaction ID greater than 0x007F. In such cases, instead of including the same Transaction ID in the response, the router includes, for example:

router query: 0x0080

response from the router: 0xFF80 - it should be like in the question.

Below is a fragment of the communication log with the router:

[TCP]> Tx> 13: 55: 02: 459 - 00 7D 00 00 00 06 01 03 00 01 00 02

[TCP]> Rx> 13: 55: 02: 522 - 00 7D 00 00 00 07 01 03 04 00 00 0C 47

[TCP]> Tx> 13: 55: 02: 637 - 00 7E 00 00 00 06 01 03 00 01 00 02

[TCP]> Rx> 13: 55: 02: 691 - 00 7E 00 00 00 07 01 03 04 00 00 0C 47

[TCP]> Tx> 13: 55: 02: 822 - 00 7F 00 00 00 06 01 03 00 01 00 02

[TCP]> Rx> 13: 55: 02: 891 - 00 7F 00 00 00 07 01 03 04 00 00 0C 47

[TCP]> Tx> 13: 55: 02: 991 - 00 80 00 00 00 06 01 03 00 01 00 02

[TCP]> Rx> 13: 55: 03: 054 - FF 80 00 00 00 07 01 03 04 00 00 0C 47

Sys> 13: 55: 08: 055 - Error: Invalid data

[TCP]> Tx> 13: 55: 08: 139 - 00 81 00 00 00 06 01 03 00 01 00 02

[TCP]> Rx> 13: 55: 08: 207 - FF 81 00 00 00 07 01 03 04 00 00 0C 4D

Sys> 13: 55: 13: 225 - Error: Invalid data

[TCP]> Tx> 13: 55: 13: 225 - 00 82 00 00 00 06 01 03 00 01 00 02

[TCP]> Rx> 13: 55: 13: 294 - FF 82 00 00 00 07 01 03 04 00 00 0C 52

Sys> 13: 55: 18: 309 - Error: Invalid data

[TCP]> Tx> 13: 55: 26: 379 - 00 83 00 00 00 06 01 03 00 01 00 02

[TCP]> Rx> 13: 55: 27: 510 - FF 83 00 00 00 07 01 03 04 00 00 0C 60

Sys> 13: 55: 32: 525 - Error: Invalid data

by anonymous
Thank you for the details I will forward this information to R&D.
by
Thank you for your reply and I am waiting for a positive solution to the problems reported.