In an R2 Niagara station, trying to write a setpoint to a holding register in a Modbus controller, received an error Illegal Data Address.

Issue

In an R2 Niagara station, trying to write a setpoint to a  holding register in a Modbus controller, received an error "Illegal Data Address".

Product Line

TAC I/A Series

Environment

R2 Niagara integration to a Modbus controller.

Cause

Not known.  The procedure in the Resolution has been used successfully with a Siemens PLC and with a Thermax chiller controller.

Resolution

  1. Go to the Properties of the Modbus Asynch Service
  2. Go to the General, Config tab
  3. Set the value of the usePresetMultipleRegister = True
  4. "Apply" to save changes.