• Up to 15 hardware selectable slave addresses
    • 1 software selectable slave address
  • 9600, 19200, 38400, or 115200 baud rate
  • Hardware selectable parity of "none" or "even"
  • 8 data bits & 1 stop bit
  • 35mm DIN rail mountable unit
  • 24VDC ±15% power supply
  • 5-year guarantee & CE approved


The Define Instruments RIO-MOD-RTU distributed I/O station is capable of providing 16 isolated relay outputs and 16 digital inputs. The isolated relay outputs are Form C change over (10A 250VAC or 10A 30VDC) with a 1kHz scan rate. The relay state is software selectable and features an auto shutoff. The digital inputs have a 1kHz sample rate, an input voltage of 5 to 24V, and can be set to NPN (sink) or PNP (source). There are LED indicators on each of the relay outputs and digital input channels for commissioning and fault finding.

This unit can be used as a remote terminal unit for any Modbus system and supports the following Modbus function codes:

  • 1 - Read single coils
  • 2 - Read single discrete inputs
  • 3 - Read holding register
  • 4 - Read input register
  • 5 - Force single coil
  • 6 - Write single holding register
  • 15 - Force multiple coils
  • 16 - Write multiple holding register


This product can be used in the following applications: