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Published 20 hours ago • verified publisher icon arduino-libraries

Problem with single coil functions

Open Nickyy-b opened this issue 5 years ago • 4 comments

Hello sandeepmistry,

I need your help with this problem, I've managed to master a good part of the Arduinomodbus library, and in C language I have a great knowledge, but I really can't get over this problem, in example (ModbusRTUClientKitchenSink), after the void loop you specified functions for write a single coil, read single register, etc.(the comments after the voids of each function) I am trying to use ModbusRTUClient.coilread, and also .write, but it returns me -1 or some strange character, sometimes does not return anything, other functions I use normally, but these I can't. Thanks if you can help me. I am using an Arduino mega 2560 as client, and a pro mini as server, I do not think the problem is in one of them because so far the Arduinos have done several things I did with this library, I will attach the part of the code as image. I don't know if I'm making a stupid mistake, don't notice my english, it's not the best :) error 1 I've done without client.read, I've used other functions but it didn't work

Nickyy-b avatar Sep 13 '19 20:09 Nickyy-b

Hi @Nickyy-b,

Could you please provide more insight on how things are wired/connected?

I also believe since the Pro Mini only has a single Serial instance, any sketches should avoid Serial.println(...) statements and let the Modbus library have full control of the Serial port.

sandeepmistry avatar Sep 18 '19 13:09 sandeepmistry

Thanks for replying, sorry for the delay in returning. I connected the client (Mega) and the server (Pro mini) directly Rx to Rx and Tx to Tx, that programming I attached is from mega, and the Serial window is the answer from Pro mini (server) returns to mega. The programming of the server is modified only with a char that makes a led flash, just this, I'm not using serial.print, strangely only this function of reading a single coil is returning me -1, the others read / change multiple registers / Coils work normally, I can change to read less than 10, 3 for example, but ModbusRTUClient.coilread returns me -1, can you help me?

Nickyy-b avatar Sep 25 '19 21:09 Nickyy-b

@Nickyy-b please share the exact sketches you are using. Are you able to also use a logic analyzer to trace what is being sent and received on the wire?

sandeepmistry avatar Oct 07 '19 14:10 sandeepmistry

The codes !! Edited.zip

What didn't catch was the function in "if serial == d", this function returns me -1. Do you think I can replace it with the requestFrom function or RTU.beginTransmission, without any problem?

Nickyy-b avatar Oct 16 '19 01:10 Nickyy-b