Hello, how can i define the UNIT ID in the modbus functionality ETHERNET ?
I can't find documentation about this parameter.
Best regards, Ennio
Another solution is to use modbus library request like Jacobs tutorial (with Portenta and not Opta for exactly).
I'm arrive at this situation without documentation :
I didn't analyze frame modbus from Opta but with node 255 instead 1, it's impossible obtain answer from the modbus device.
https://www.axelsw.it/pwiki/index.php/Configuration:_Modbus_TCP
Ops, PLC IDE hasn't some declaration field ? We wait an official answer.
Bye
Ennio
I'm having the same issue. You can define Unit ID using RS485 and that seems to work fine, but the lack of Unit ID using Modbus TCP makes it impossible to talk to my ethernet devices.
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Unit identification seems to be fixed at 255 for now
Unit identification can be changed once the Modbus Master setting is cancelled.
After that, it will be reflected when you set it to Modbus Master again. I think it's an IDE issue
@yoshinobu1 i talk about client ID unit with Opta like master not ID unit OPTA, it' s not the same. Tomorrow i will try some test with simulator and PLC.
Hello, today i replicated Jacob's video about Modbus TCP comunication to a PLC.
This is easy with a PLC beacuse its library adapt the answer with request's unit id.
But the question is always the same : where can i declarate the ID unit (in Opta case, the slave ID), in PLC IDE ?
Finally got this working with my OPTA.
Instead of using Generic Modbus from the catalog, I ran the Modbus Custom Editor from the tools dropdown. This will let you create a new catalog object for both Modbus TCP and RTU. I set up all of my registers in the Modbus Custom Editor and saved it. Then under ethernet I added the new catalog object, that then allowed me to set up my device's IP address and Unit ID. It's now working great over Modbus TCP to talk to my devices.
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Well done.
Would you consider please uploading your demo program or some screenshots?
I'm trying to make Modbus RTU work but I assume it's the same issues.
Hello, but this problem (costant unit ID) is on Modbus TCP not RTU.
Ennio
Attached is a program I recently made that dealt with the issues noted in this thread. This program polls three different modbus TCP devices, all of them at the same IP address. The data from those devices is then converted using FBD to a format readable by a Kinco HMI that communicates with the OPTA via Modbus RTU on the RS485 port. This program shows the use of both the TCP port and RS485 port for modbus comms. This program is basically a Modbus TCP to Modbus RTU gateway to allow an HMI to display variables collected from a Victron microgrid.
@jwballison I have not noticed much, if any limitation in using Modbus RTU using PLC IDE. As you can see in my program, I did not have to use a custom library to make it work. Only have to use custom libraries on Modbus TCP to make it work.
Victron to Kinco HMI bridge.zip (5.7 MB)
"Hello grosspolliter, how did you manage timeout RTU communication over 11 failovers?
I saw that you used Modbus Editor, which enables the UNIT ID field instead. This information can be used for TCP to RTU communication, whereas in generic Modbus, the unit field is constant! Unbelievable.
It's also unbelievable that I couldn't find any information about this tool (Modbus Editor) and translating/adapting AxelWiki.
Best regards
Hi @enrob
Unfortunately I have not encountered the issue with the RTU communication timeout, so I do not have an immediate suggestion. I do believe the PLC IDE software leaves a bit to be desired and hopefully being a 3rd party program it can be developed to better accommodate the Arduino products.
Everything I have learned about PLC IDE so far has been the result of trial and error since the documentation is lacking. It would be nice to be able to reset the Modbus RTU comms without having to reset the entire device. At this point the solution may require some structured text or a function block to be able to accomplish this, even though a setpoint would be more appropriate.
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PLC IDE by Arduino is too young for industrial use. It's not possible to leave all the functionality development to the users, but for a simpler reason: the resources are available in the source code (Axel Logic Lab). I have used this development software with many other devices (Parker, Pixys, Elsist), and I have never encountered these problems.
It would be nice to be able to reset the Modbus RTU comms without having to reset the entire device
I bought a device for testing in March, and now (almost June), I'm starting up a small automation project with Siemens S7 1211 instead of an Opta device. The automation involves a device without an operator, with cloud connection and remote assistance. This setup is ideal for Opta Finder hardware, but not for its software.
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