The Novus DigiRail Connect DMIX 8DI / 8DO (8811612420) adds 8 digital inputs and 8 PNP transistor outputs to almost any PLC, SCADA or data logging system, over Ethernet (Modbus TCP) or RS485 (Modbus RTU). Inputs accept PNP, NPN or dry contact signals and can be configured as pulse counters, and outputs can be set for pulse operation, making it a compact way to add discrete I/O wherever a controller has run out of points.
Every DigiRail Connect model has Ethernet, RS485 and Micro USB on board. It works as a Modbus RTU slave on an existing RS485 network or as a Modbus TCP server on Ethernet, and can act as a transparent Modbus TCP to RTU gateway, so an Ethernet PLC or SCADA system can read RS485 instruments wired to its terminals with no register mapping. Configuration and I/O testing use free Novus NXperience software over USB.
Lead time: made to order by Novus, typically 1–2 weeks to dispatch.
DigiRail Connect Range
All four DigiRail Connect models share the same Ethernet/RS485 hardware and software. Choose by the I/O mix you need:
- DMIX 8DI / 8DO (8811612420) — this model: 8 digital inputs, 8 PNP transistor outputs
- DMIX 8DI / 4 Relay (8811612440) — 8 digital inputs, 4 relay outputs
- RAMIX 2AI / 2AO / 4DI / 3DO (8811611420) — 2 universal analogue inputs, 2 analogue outputs, 4 digital inputs, 3 PNP outputs
- RAMIX 2AI / 2AO / 4DI / 2 Relay (8811611440) — as above with 2 relay outputs
Only need analogue inputs on RS485? The lower-cost Novus DigiRail-2A converts two thermocouple, Pt100, mV, V or mA signals to Modbus RTU.
✅ 3 Year Manufacturer Warranty — backed by our UK-based technical support
Novus DigiRail Connect Datasheet Download
Novus DigiRail Connect Manual Download
Technical Details
Order code: 8811612420 (DigiRail Connect DMIX 8DI / 8DO ETH)
Digital inputs: 8, PNP, NPN or dry contact, configurable counter function
Digital outputs: 8, PNP transistor, 200mA max load per output, 6-30 Vdc switching, configurable pulse function
Communication: Ethernet 10/100 Mb/s (IEEE 802.3u), RS485, Micro USB
Protocols: Modbus TCP server, Modbus RTU slave, transparent Modbus TCP to RTU gateway
Configuration software: Novus NXperience (free, via USB)
Power supply: 10-36 Vdc, 5W max (20mA typical)
Operating conditions: -20 to 60°C, 5-95% RH non-condensing
Enclosure: ABS+PC, 35mm DIN rail mounting
Frequently Asked Questions
Should I choose this 8DO model or the DMIX 4 Relay model?
The 8DO model has PNP transistor outputs (up to 200mA each) for driving PLC inputs, interposing relays and indicator lamps. If you need volt-free contacts or to switch AC loads, the DMIX 8DI / 4 Relay model is the better fit.
Can the digital inputs count pulses?
Yes. Each input can be configured as a counter in NXperience, which suits flow meter pulses, production counts and run-hour monitoring.
Can it bridge RS485 devices onto Ethernet?
Yes. In gateway mode it passes Modbus TCP requests to RTU slaves wired to its RS485 terminals with no register mapping, so an Ethernet PLC can read existing RS485 controllers and meters.
What happens if communication is lost?
A configurable watchdog drives the outputs to a defined safe state if the Modbus master stops communicating.
Industry Applications
- Machine & line monitoring — counts parts and reads sensor and limit switch status for OEE or production reporting.
- PLC I/O expansion — adds 16 discrete points to a PLC over Ethernet without a rack expansion.
- Building services — reads plant status contacts and switches pumps and fans through interposing relays on BMS networks.