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Are TCP/RTU adapters supported? #20

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andig opened this issue Dec 20, 2019 · 3 comments · Fixed by #21
Closed

Are TCP/RTU adapters supported? #20

andig opened this issue Dec 20, 2019 · 3 comments · Fixed by #21

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@andig
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andig commented Dec 20, 2019

I'm trying to use a Waveshare RS485 to Ethernet adapter, but fail to connect to the device (i/o timeout). Using this lib it seems I'm actually communicating like this:

    modbus TCP     modbus RTU
client ----> adapter ---->device

Now I've seen goburrow/modbus#42 and was wondering if that's how that works. Do these adapters typically convert modbus TCP to modbus RTU or do I need to "speak" RTU over TCP for that to work?

In other words: is the ref'ed PR relevant for this repo?

@frzifus
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frzifus commented Dec 20, 2019

i would guess that they are using modbus tcp and the device adds the checksum by itself. But even if not it should not be a big problem to transfer the checksum. Is there no online documentation for the device?

@andig
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andig commented Dec 21, 2019

i would guess that they are using modbus tcp and the device adds the checksum by itself.

Thought so. Might be that the device is just broken, I'll return it and try a different brand.

@andig andig closed this as completed Dec 21, 2019
@frzifus
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frzifus commented Dec 21, 2019

i would suggest to monitor the input and output of the device. There you should see if the crc is added or not 👍

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2 participants