I am trying to use an iot edge device connected with a VM along with the iot edge modbus module to act as a gateway to store data from my Modbus device to my hub. I believe I have everything set up I just can't seem to get my Modbus device and Modbus module to connect. I am attaching screenshots of my configurations and troubleshooting of my modbus module. Any help would be appreciated thank you!

Hello @Stross, Jared , you can read telemetry from a device supporting the Modbus protocol (both TCP and RTU) using the Microsoft Modbus module. Keep in mind you both have to add Container create options for RTU too (see this GitHub section). Check the module logging for more details to see it you get a response: iotedge logs -f Modbus See also this blog post (it's an older blog so ignore the old module name).

IOT Edge Modbus Module - Microsoft Q&A

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Sander van de Velde | MVP 33,146 Reputation points MVP

2022-08-10T21:21:55.377+00:00
Hello @Stross, Jared ,

you can read telemetry from a device supporting the Modbus protocol (both TCP and RTU) using the Microsoft Modbus module.

Keep in mind you both have to add Container create options for RTU too (see this GitHub section).

Check the module logging for more details to see it you get a response:

iotedge logs -f Modbus

See also this blog post (it's an older blog so ignore the old module name).
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Stross, Jared 41 Reputation points

2022-08-11T14:51:01.563+00:00

Hello @Sander van de Velde | MVP

Do I need a static IP address in the configuration? I feel like I would to help the modbus device and module communicate, but I don't see one anywhere in the configurations of the device twin.

Thanks you!

Sander van de Velde | MVP 33,146 Reputation points MVP

2022-08-11T19:23:56.507+00:00

Hello @Stross, Jared ,

the modbus edge module pulls data from the device that exposes the modbus coils and registers.

In the slave connection, you enter the IP address of that device (can you ping the device from your edge over that IP address?).

So, it's recommended to give the modbus device a fixed IP address, so you do not have to update the module twin.

In this case, there is no need for a fixed IP address for the edge. It only makes 'outbound' calls in this situation.

Note: the device twin of an edge device has no use, the modules are the ones that run the logic.

Stross, Jared 41 Reputation points

2022-08-12T11:27:06.957+00:00

@Sander van de Velde | MVP Thank you that cleared up a lot for me. I just realized the problem I am having, the modbus module isn't able to pull from my device because of the firewall. Is there any way around this, maybe a VPN or proxy?

Thanks!

Sander van de Velde | MVP 33,146 Reputation points MVP

2022-08-12T14:12:50.683+00:00

Hello @Stross, Jared ,

I have no information about your network topology.

Normally, an Edge device has access to two non-bridged networks: one for the cloud and one for the local devices.

Check your network cards on the edge device if an IP address is provided in the same range as your modbus device.

Then try to ping your modbus device. Normally modbus devices are allowing this.

Contact your network administrator if in doubt.

He/she can help you with firewall settings. A VPN is a heavy solution so I recommend to keep it simple first.

In our projects, we run simulations of actual devices if possible. These can even run on a docker container, on the edge. Using the IP address of the device you can reach it from one module to another. This works great for Modbus TCP.

Check out this simulation as example application.
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