MAX 485 Modbus request/responce

Hi, everybody.
I need your help, i'm new at arduino. I have a water level meter which it's output rs485 Modbus. i've to get measure level from device. For get data from sensor i must to request command 01 03 00 01 00 01 D5 CA by device data sheet. Reply data will be 01 03 02 0F 2E 3D A8, here distance is 0X0F2E (HEX), 3886mm (DEC). I read some article about Modbus protocol, but i coudn't.

Now i've arduino uno, MAX 485:
RO -> Pin Rx
RE, DE -> Pin 4
DI -> Pin Tx

PLS help me to solve this.


Take your time to read this:

The level of information you gave, does not allow much help beyond:

  • send the request
  • receive the response
  • extract the needed data