Novus Automation offer 3 models of simple RS485 IO module:
- DigiRail 2A — 2 x universal analogue input
- DigiRail 4C — 4 x digital inputs/counters
- DigiRail 2R — 2 x 8A SPDT relay outputs
Devices are DIN rail mounted and require very basic parameter setup using free DigiConfig software, allowing easy expansion of existing I/O and integration as a Modbus RTU Slave, reading and writing the registers accordingly.
The DigiRail line of smart transmitters with Modbus RTU communication interface provide a simple way to integrate analogue or digital signals into supervisory systems. Featuring up to two universal input analogue signal channels, they're one of the most economical ways to deliver analogue inputs to PLCs and SCADA systems. The input signals are isolated from power, protecting electrical instruments by eliminating ground loop effects and substantially reducing undesirable interferences and instabilities in sensor measurements.
✅ 3 Year Manufacturer Warranty — backed by our UK-based technical support
Technical Details
Analog inputs: programmable for thermocouples (J, K, T, E, N, R, S, B), Pt100, mV, V, mA
Cold junction compensation for thermocouples and compensation for Pt100 3-wire cables
Open loop detection for thermocouples, Pt100, and mV
Sampling rate for 1 analog input: 10Hz for mV, V, and mA; 5Hz for thermocouples and Pt100
Analog input resolution: 17 bits
Digital inputs: 4 to 35V to activate, internally limited to 5mA
Digital outputs: 8A / 250Vac SPDT relay, resistive load
Power: 10 to 35 Vdc, 50mA max current. 2-wire RS485 communication with Modbus RTU protocol
Configurable address and baud rate (1,200 to 115,200bps)
LED indicators for communication and status. Key for resetting communication parameters to factory default
Accuracy (@25°C): Pt100, mV, V, mA ±0.15% of full scale; Thermocouples ±0.25% of full scale
Temperature effect: 0.003% of full scale/°C. Cold junction compensation for thermocouples: 1°C at 25°C, ±0.05°C/°C
Isolation: 1000Vac between inputs (analog or digital) and power/communication
Windows-based configurator software (free download)
Dimensions: 72 x 78 x 19mm. Mounting: 35mm DIN rail. Working temperature: 0 to 70°C
Frequently Asked Questions
Which model do I need — 2A, 4C, or 2R?
DigiRail 2A adds analogue inputs (thermocouples, Pt100, mV/V/mA), DigiRail 4C adds digital inputs or counters, and DigiRail 2R adds 8A relay outputs — pick based on the signal type you need to add to your Modbus network.
Do I need special software to configure it?
No — free DigiConfig Windows software handles the basic parameter setup, including address and baud rate.
Does it work as a Modbus Master or Slave?
Slave — DigiRail modules integrate as a Modbus RTU Slave, with an existing Master reading and writing the registers.
Industry Applications
- Modbus I/O Expansion — adds analogue, digital, or relay I/O to an existing RS485 network economically.
- SCADA & PLC Integration — isolated inputs protect sensitive control equipment from ground loops.
- Panel Building — DIN rail mounting for compact control panel integration.