RS485 modbus connection timed out

Official Hardware Opta
1

I am trying to read a Modbus energy meter (QEED) with a Arduino Opta. Somehow I keep getting the error 'Connection timed out'.

Arduino A- connected to A+ on energy meter, Arduio B+ connected to B- on energy meter.

From my understanding this should be the right call for reading the address of the device:

if (!ModbusRTUClient.requestFrom(0x01, HOLDING_REGISTERS, 0x02, 1)) {

From documentation of the meter:

ADDRESS LIST BASE 1 (40001)
MICROPROCESSOR'S REGISTERS BASE 0 (0000)
EXAMPLE _ to read register 40003 (address device = 1)
Tx: <01> <03> <00> <02> <00> <01> <25> <CA>

I adjusted the 0x0002 to different values but keep getting connection timed out. Any suggestions?

2

Hi @mark89769 ,

Please take a look at the following tutorial:

Energy Management with Opta™

I hope you find it useful.

Best,

3

Hi, This is Jeong-moo Hwang who want to code the Arduino OPTA.

I would like to ask some question regarding the problem that you suffered. Did you solve the problem ??

Actually I send the correct Slave ID, Address, Fuction code from OPTA(Master) to relay channel(Slave). However, The CRC code was wrong. There are CRC error..

Therefore, I try to code by using Arduino IDE. In this case, there are error messages like "failed! Connection timed out".

If you solve the problem, could you help me ??

Sincerely,

4

Maybe you should post your code, your hardware and your modbus protocol.