Author Topic: Modbus RTU on TWR-K20D72M  (Read 16368 times)

Offline Felix

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Re: Modbus RTU on TWR-K20D72M
« Reply #15 on: February 04, 2018, 07:07:33 PM »
Hi Mark,

I think I almost have it now!  :D
You was right (again ;) ) with the short circuit (it was on the soldering) and I had to change some things in the example.
There´s some communication on all lines now and the slave answers at the given address. Unfortunately there´s still a little problem. How you can see in the attached image the master receives just semi-valid messages. Some bytes are not received correctly, but the Modbus settings on both devices are equal.
Can I fine-tune the timing somehow? Or maybe I'm still doing something wrong?

Best Regards
« Last Edit: February 04, 2018, 10:45:02 PM by Felix »

Offline mark

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Re: Modbus RTU on TWR-K20D72M
« Reply #16 on: February 05, 2018, 02:03:46 AM »

At 9600 Baud there should be no issues with speed/timing.

If I understand it correctly there are responses (RX) but they don't look to be reliable in some way. I would therefore carefully check the RS485 direction control and signal integrity - at least the response should be identical in each case.