PM4DIRO - 4 Digital Input/ Relay Output Module

The PM4DIRO module is an 4 channel digital input and 4 channel relay output module.

The inputs are isolated from the logic by bi-directional opto-couplers. The common can be connected to either the -volts or +volts field power supply terminals.

The inputs have internal counters associated with them. These counters are 32 bit counters allowing a count value from 0 to 4294967295. The count value can be cleared by writing a zero to the associated registers or preset to any other value using the same method.

Note: The count values are not battery backed-up and will be lost if power is turned off.

The format of the registers allows the status of the inputs to be read as either single bits or all at once as a single register on the Modbus network.

The 4 relay outputs provide normally open and normally closed contacts. The outputs may be used to drive lamps or external relays when more drive capability is required. The outputs are isolated from the logic.

The module may be used as either a slave or master on the Modbus network. When used with a PC or PLC the module will be configured as a slave. When used with another PM4DIRO module in a point-to-point configuration, the DIP switch 9 must be turned on to set the module up as a master. In this mode the PM4DIRO module will automatically read/write the information from/to the other PM4DIRO module.

When used as a slave module, the outputs are written to by the Modbus master device such as a PC or PLC. Each output can be individually switched on or off, or all outputs can be set up at the same time by writing a single number to the output register which represents the status of all outputs.

PM4DIRO - 4 Digital Input/ Relay Output Module

Digital Inputs


Digital Counters


Counter Resolution

32 Bit

Counter frequency

1 KHz (max)

Pulse width

500usec (min)

Counter Mode


Digital input 0 level

0 to +6.5Vdc

Digital input 1 level

+12Vdc to +24Vdc

Input Impedance

2200 ohms

Input filter

Max 6553 msec.

Status Indication – inputs

LED per channel

Relay Outputs



Form C

Max Load Current

1A / 2A

Max load Voltage

220VAC / 24VDC

Isolation (Contacts)


Isolation (Field & Logic)


Watch dog output timer

Disable or 1-255 sec adjustable

Status Indication – outputs

LED per channel

Power supply


Order Codes

  • PM4DIRO - PROMUX 4 Digital Input/ Relay Output Module

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PM4DIRO - 4 Digital Input/ Relay Output Module

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Procon Electronics