ALLEN BRADLEY 1738-OB4EM8 Product Description

Overview

ALLEN BRADLEY 1738-OB4EM8 is a Rockwell Automation ArmorPoint 1738 Series A 24 V DC digital output module. The module provides 4 sourcing digital outputs in a sealed ArmorPoint on-machine I/O housing with M8 pico connectors. It is a distributed I/O output spare for existing Allen-Bradley PLC, scanner or EtherNet/IP ArmorPoint systems, supplying DC outputs to solenoid valves, contactor coils, indicator lamps, relays, motor starters or other 24 V DC field loads.

Features

The 1738-OB4E module family provides four non-isolated sourcing outputs. External DC power supply range is 10 to 28.8 V DC, nominal 24 V DC. On-state output current maximum is 1.0 A per channel, electronically protected; for 1738-OB4E modules the total module rating does not exceed 3.0 A maximum. Minimum on-state output current is 1.0 mA per channel.

Output voltage ranges: off-state maximum 28.8 V DC, on-state nominal 24 V DC, on-state maximum 28.8 V DC, on-state minimum 10 V DC. On-state voltage drop maximum is 0.2 V DC for sourcing modules. Off-state leakage current maximum is 0.5 mA. Output surge current is 2 A for 10 ms, repeatable every 3 seconds per the ArmorPoint specification.

The 1738-OB4EM8 connector uses M8 pico pinout: Pin 1 is 24 V DC, Pin 3 is Common, Pin 4 carries Output 0, Output 1, Output 2 and Output 3 on M8 channels A to D per the Rockwell installation instructions. The module consumes external DC supply current 16 mA for a 4-connector module. PointBus current maximum is 75 mA at 5 V DC.

I/O status LEDs indicate output and network or module status. Yellow or red output status LEDs provide open-circuit, no-load or output indication; flashing red indicates open-circuit detection or no load in off-state only according to the manual. Network and module status LEDs are green or red. Output delay time is maximum 0.1 ms, OFF to ON and ON to OFF.

Specs

Brand: ALLEN BRADLEY / Rockwell Automation Family: ArmorPoint 1738, Series A Model: 1738-OB4EM8Product type: 24 V DC digital output module Outputs: 4Output type: Sourcing, non-isolated Connector: M8 picoExternal supply voltage: 10 to 28.8 V DCNominal supply: 24 V DCPer-channel on-state current: 1.0 A maximum, electronically protected Module maximum output current: 3.0 A for OB4E family Minimum on-state current: 1.0 mA per channelOff-state output voltage: Maximum 28.8 V DCOn-state output voltage: Nominal 24 V DC, range 10 to 28.8 V DCOn-state voltage drop: Maximum 0.2 V DCOff-state leakage: Maximum 0.5 mAOutput surge: 2 A for 10 ms, repeatable every 3 seconds External supply current: 16 mA for 4-connector module PointBus current: Maximum 75 mA at 5 V DCOutput delay: Maximum 0.1 ms either direction Power dissipation: 1.2 W maximum at 28.8 V DC for OB4E Thermal dissipation: 4.1 BTU/hour maximum at 28.8 V DC Dimensions including module and mounting base: 120 H × 72 W × 42 D mm; 4.72 × 2.82 × 1.65 inWeight: 0.29 kg; 0.64 lbEnclosure rating: Meets IP65 / IP66 / IP67 when marked Mounting base: #8 or M4 screw; torque 7.5 in. lb aluminum, 16 in. lb steel Operating altitude: To 2000 m without derating per manual Control category: Overvoltage Category II, IEC 60664-1 Emissions: CISPR 11 Group 1 Class A Certifications: c-UL-us industrial control equipment, CE, C-Tick when marked I/O message: Output modules produce 1 byte status and consume 1 byte I/O data Product status: Existing ArmorPoint distributed output module spare

Principle

The ArmorPoint output module receives output commands over PointBus or the distributed I/O network from the PLC scanner or EtherNet/IP adapter. Each sourcing transistor channel switches the positive 24 V DC field supply to the connected load; the load return connects to the module common. Electronic channel protection limits overcurrent, and status LEDs communicate output, open-circuit or network condition for panel-free on-machine diagnostics.

Replacement should verify the ArmorPoint adapter or scanner compatibility, module slot or address, source versus sink output, M8 connector pinout, 24 V DC supply capacity, per-channel and total module current, inductive load suppression, cable category, grounding, I/O data mapping, LED diagnostics and any machine safety or interlock wiring. The module is sealed for on-machine mounting, but connector protection and cable entry must maintain the listed enclosure rating.

Applications

ALLEN BRADLEY 1738-OB4EM8 is used in existing ArmorPoint distributed I/O installations on conveyor lines, packaging machines, material handling, machine tools, packaging and filling equipment, assembly stations, robotic cells, process skids, tire or textile machinery, automotive manufacturing and factory automation panels. In legacy Rockwell systems, it serves as a direct replacement 4-point sourcing output spare when the adapter, connector, supply voltage, current rating, I/O map and mounting arrangement match the original module.