search

bertmelis / esp32ModbusRTU

modbus RTU client for ESP32
MIT License
70 stars 44 forks source link

Getting error: 0xe0 #23

Closed Tsaadon closed 4 years ago

Tsaadon commented 4 years ago

Hey, I used the example you provided, changed only the address and slave ID but I get this error, what does it mean? Thanks.

bertmelis commented 4 years ago

Timeout. Try to swap A and B wires.

Tsaadon commented 4 years ago

Tried, still the same error :\, I know for sure the sensor is good because I connected it to the PC using a USB adapter and Modbus tester software and I get good output. Do you have any idea what else could be causing it? According to the producer (and what worked using the PC), Slave ID 1, I need to read address 0x0000-0x0002, Buadrate 9600, 8 data bits, 1 stop, no parity.

bertmelis commented 4 years ago

Well, if you're getting a timeout, the esp is not receiving any data.

Are you using a line driver (max3485 or similar)? Which kind? Do you have a logic analyzer?

Tsaadon commented 4 years ago

Yes, I'm using the max3485 by SparkFun, and no, no logic analyzer on hand. https://www.sparkfun.com/products/10124 When the "sending Modbus request.." appears on the serial monitor the RTS LED on the max3485 blinks, if that helps in anyway..

Miq1 commented 4 years ago

Did you connect A and B only or GND as well? Did you terminate the RS485 on the max3485 module side (120 Ohms between A and B, 1kOhms between A<->Vcc and B<->GND)? Both may stabilize the signal. If you have a multimeter at hand, try to measure the voltage difference between A and B. It should vary when you are sending a request as well if a response is received.

bertmelis commented 4 years ago

I did like in the readme, so yes I used the termination resistors as well as biasing resistors. I also connected GND. Keep in mind that I've not drawn the "other side of the line". There must also be a 120Ohm resistor.

I didn't use a breakout board but a bare max3485. Maybe your board already has some resistors.

Miq1 commented 4 years ago

:) I was referring to the post of Tsaadon, not yours. Sorry, should have made that clearer.

I personally have added the resistors despite the fact that I used a module - it resulted in a clearer signal.

bertmelis commented 4 years ago

Oops, didn't notice. Working on phone while enjoying a view on the Tatra mountains.

Tsaadon commented 4 years ago

I didn't connect GND and tried adding the resistors, we tried the voltmeter, and played a bit with turning from send to receive and it seems to work, no idea what the issue is. Some friends helped me with a different code (but the same library) and now it's working. Thanks for the help guys!

bertmelis commented 4 years ago

:+1: