Digital I/O module romod 4DIO-R

RS-485serialModbus RTU

Product overview
The romod 4DIO-R is a DIN-rail mounting module providing four digital inputs and four relay digital outputs. It functions as a Local Override/Indication Device (LO/ID) for control and signalling tasks and supports manual override via integrated switches in addition to Modbus RTU control.

Digital outputs

• Four relay outputs with normally open (NO) contacts.
• Switched signals must share the same phase reference.
• Outputs can follow digital inputs (configurable) in addition to Modbus-controlled commands.
• Supports static control and toggling; on/off delays and minimum on/off times configurable per output.
• Configured delays and minima apply to bus-activated switching; manual override bypasses these safeguards.
• Mutual interlocking of outputs is supported.
• Each output has an LED status indicator.
• Safe-state behaviour configurable: outputs may assume a defined state if Modbus telegrams are not received within a configurable timeout.

Digital inputs
The four digital inputs accept 24 V signals switched by external dry contacts via terminals. Reference potential is defined via COM terminals (0 V or 24 V). When using 24 V reference, inputs can be driven with 0 V. Input logic (open-circuit or closed-circuit) is selectable via Modbus registers. Inputs may be used as non-retentive counters; minimum pulse width for reliable DC detection is 10 ms. For AC input control, edge detection delay must be configured.

Additional features and behavior

• Switch positions readable via registers; a register flags switches operated since last read.
• Outputs can be configured with safe-state behaviour for bus timeouts; ensure timeout settings avoid unintended activations.
• Configuration stored in internal EEPROM (up to 100,000 write cycles).

Technical specifications

• Manufacturer: romutec Steuer- und Regelsysteme GmbH
• Product number / SKU: 00002955
• Model: romod 4DIO-R
• Weight: 0.156 kg
• Supply: 24 V AC/DC via terminals
• Current consumption: typically 68 mA (DC), 152 mA (AC) with all relays active
• Power dissipation: max. 1.7 W (DC), 3.7 W (AC) with all relays active
• Digital outputs: relay (NO), max. 250 VAC
• Initial contact resistance: 100 mΩ (at 1 A / 24 VDC)
• Rated load: 3 A at 250 VAC / 30 VDC
• Max. switching voltage: 277 VAC, 30 VDC
• Max. switching capacity: 830 VA (AC), 90 W (DC)
• Endurance: 100000 operations (rated load)
• Avoid or suppress inductive loads at source
• Counting pulse duration (DC): min. 10 ms
• Max. counter value: 4,294,967,296 (counter not retained on power loss)
• Bus interface: RS485
• Supported baud rates (autobauding): 9600; 19200; 38400; 57600
• Protocol: Modbus RTU (RS485), serial 8-N-1
• Configuration stored in internal EEPROM (max 100,000 write cycles)
• Operating temperature: 0…50 °C
• Transport/storage temperature: 0…70 °C
• Relative humidity: 10…90% non-condensing
• Protection class: IP20