Allen-Bradley 1734-OW4 — POINT I/O Relay Output Buying Guide

By Abdullah Zahid
16 min read
Allen-Bradley 1734-OW4 POINT I/O 4-point relay output module for mixed AC DC load switching in industrial automation panels

Allen-Bradley 1734-OW4 POINT I/O 4 Point Digital Output Module (4 Relay Outputs) — Specs, Selection Guide & Where to Buy

Controls engineers and procurement specialists searching for the Allen-Bradley 1734-OW4 are typically at the final stage of a module selection decision: they know they need relay outputs in a POINT I/O rack, and they need to confirm the 1734-OW4 is the right part before placing the order. This is a POINT I/O 4-point digital output module providing four isolated Form A (normally open) relay contacts for switching AC or DC field loads — contactors, solenoid valves, pilot lights, and interposing relay coils — without drawing load power from the internal POINTBus. It clips onto a compatible POINT I/O terminal base and communicates through any supported network adapter, fitting naturally into existing Logix and POINT I/O architectures.

If you have already confirmed this is the right part, check current pricing and availability for the 1734-OW4 at LeadTime.ca — ships worldwide.

Who Should Buy the 1734-OW4 — and Who Shouldn't

The Allen-Bradley 1734-OW4 is the right choice when your application demands isolated dry contact relay outputs within a POINT I/O distributed I/O rack. Order this module if your project meets all of the following criteria:

  • You need relay (dry contact) outputs — not transistor sourcing or sinking — for galvanic isolation between the controller and the field device.
  • Four output channels are sufficient for the machine segment or I/O drop being designed.
  • Your loads include a mix of AC and DC voltages, or mains-level AC that transistor modules cannot handle.
  • You are working within an existing Allen-Bradley POINT I/O architecture with a compatible network adapter (EtherNet/IP, ControlNet, DeviceNet, or PROFIBUS) and a Logix or supported controller.
  • Switching frequency is low to moderate — this is an electromechanical relay module, not suited to high-cycle applications.
  • Panel environmental conditions fall within the -20 to 55 °C operating temperature range and 5–95% non-condensing humidity rating.

If your application is DC-only with high switching frequency and high point density requirements, the 1734-OB8 or 1734-OV8 transistor output modules are the more appropriate choice. If you need only two relay channels, the 1734-OW2 is the correct variant rather than carrying unused points in the rack.

On this page:

What the 1734-OW4 Actually Does in a POINT I/O System

The Allen-Bradley 1734-OW4 is a member of the POINT I/O 2 and 4 Relay Output Module family — catalog numbers 1734-OW2 and 1734-OW4, Series C — documented by Rockwell Automation as a four-point digital output module with Form A (normally open) relay contacts. Each of the four channels provides a voltage-free, isolated dry contact. That means the module itself supplies no power to the load circuit: external load power must always be wired in from an independent supply, whether 24 V DC, 120 V AC, or any other voltage within the contact's rated limits.

This architecture is exactly what makes relay outputs valuable in mixed-voltage applications. A single 1734-OW4 can simultaneously switch a 24 V DC solenoid valve on channel 0, a 120 V AC contactor coil on channel 1, and a 24 V DC pilot light on channel 2 — without any common voltage tying the circuits together. The contacts are isolated from the POINTBus and from each other, which also simplifies interfacing with third-party panels, safety relay circuits, and legacy equipment where grounding or voltage reference is uncertain.

What the 1734-OW4 is not: a high-speed switching device. Electromechanical relay contacts have finite mechanical life and switching speed inherently limited by the physical relay. For applications requiring rapid output cycling, high-frequency pulsing, or purely DC loads at high point density, transistor output modules are the technically correct choice. The 1734-OW4 earns its place in applications where isolation, voltage flexibility, and low-to-moderate switching frequency are the defining requirements.

Typical System Architecture for the 1734-OW4

The 1734-OW4 sits at the output end of the POINT I/O distributed I/O node, downstream of the network adapter and terminal bases, directly driving field devices through its relay contacts. Understanding the component chain helps engineers confirm that every element is correctly specified before ordering.

  • Logix controller (CompactLogix, ControlLogix, or equivalent) issues output commands over the backplane or Ethernet network to the POINT I/O adapter.
  • A POINT I/O network adapter (EtherNet/IP, ControlNet, DeviceNet, or PROFIBUS) receives the command and distributes data across the POINTBus to all modules in the rack.
  • A compatible POINT I/O terminal base (1734-TB, 1734-TBS, 1734-TOP, or 1734-TOPS) provides the mechanical mounting and field wiring terminations for the 1734-OW4.
  • The 1734-OW4 module plugs into the terminal base, draws its logic power from the POINTBus, and energizes or de-energizes its four relay coils based on the output data from the controller.
  • External load power is wired independently to the terminal base and routed through the relay contacts to field devices such as contactor coils, solenoid valves, indicator lamps, and buzzer circuits.

Typical Applications and Deployment Scenarios

The 1734-OW4 covers a wide range of machine-level and panel-level switching tasks where relay contacts are the correct interface. In packaging machinery, a single module frequently handles a mix of 24 V DC pneumatic valve solenoids and 120 V AC contactor coils in the same I/O drop, eliminating the need for a dedicated interposing relay panel. In automotive and automotive parts manufacturing, relay outputs provide the galvanic isolation needed between a Logix controller and third-party conveyor or lift controls that have their own voltage references.

Food and beverage processing lines use the 1734-OW4 to drive washdown-rated solenoids and audible alarms at various supply voltages, where the dry contact output avoids grounding issues common in stainless enclosures. Material handling and logistics systems use it to interface EtherNet/IP POINT I/O racks with pilot lights, stack lights, and buzzer circuits at voltages dictated by the facility's existing panel standards rather than by the controller.

OEM machine builders working with compact POINT I/O racks also use the 1734-OW4 as the default relay output block for small machines where the full rack might contain only a network adapter, one input module, and one or two output modules — keeping the panel footprint minimal while covering all discrete I/O requirements.

Application Typical Deployment
Packaging machinery Mixed 24 V DC valve solenoids and 120 V AC contactor coils on a single EtherNet/IP POINT I/O drop
Automotive assembly Dry contact interface between Logix controller and third-party conveyor panel requiring isolated relay outputs
Food and beverage processing Driving washdown solenoids and audible alarms at mixed supply voltages without grounding cross-contamination
Material handling and logistics Controlling pilot lights, stack lights, and buzzers at facility-standard voltages from an EtherNet/IP POINT I/O rack
OEM compact machine panels Single POINT I/O rack handling all local discrete relay outputs in a small footprint enclosure
Process skids and utilities Interfacing Logix outputs with external safety relay modules requiring voltage-free dry contacts

Key Specifications for Purchase Decisions

Parameter Value Notes
Catalog Number 1734-OW4 POINT I/O 4 Point Digital Output Module (4 Relay Outputs)
Product Family POINT I/O Allen-Bradley distributed modular I/O
Number of Outputs 4 relay outputs Form A (normally open), isolated dry contacts
Contact Type Form A (normally open), voltage-free Load power must be supplied externally; not from POINTBus
Load Voltage Compatibility Low-voltage DC and mains-level AC within rated limits Confirm exact voltage rating from Rockwell datasheet before design
Required Terminal Base 1734-TB, 1734-TBS, 1734-TOP, or 1734-TOPS Must be ordered separately; module does not include base
Network Adapter Compatibility EtherNet/IP, ControlNet, DeviceNet, PROFIBUS Controller and firmware version must support POINT I/O relay modules
Operating Temperature -20 to 55 °C Confirm from official Rockwell datasheet for final design
Storage Temperature -40 to 85 °C Confirm from official Rockwell datasheet for final design
Relative Humidity 5–95%, non-condensing Typical POINT I/O environmental rating

Full technical specifications are available on the product page at LeadTime.ca.

1734-OW4 vs 1734-OW2 vs Transistor Output Modules — Which One Do You Need?

The decision between relay and transistor POINT I/O output modules is one of the most common selection mistakes engineers encounter. The table below compares the 1734-OW4 against its closest siblings and the most relevant transistor alternatives to help you make the right call before ordering.

Module Output Type Channel Count Load Voltage Switching Speed Best For
1734-OW4 Relay (Form A NO, dry contact) 4 Mixed AC and DC within rated limits Low to moderate (electromechanical) Mixed-voltage loads, galvanic isolation, contactor and valve switching
1734-OW2 Relay (Form A NO, dry contact) 2 Mixed AC and DC within rated limits Low to moderate (electromechanical) Same relay characteristics with fewer points; use when rack space and point count are tightly constrained
1734-OB8 Transistor (sourcing, DC) 8 DC only High (solid-state) DC-only loads requiring fast switching, high point density, or high-cycle duty
1734-OV8 Transistor (sinking, DC) 8 DC only High (solid-state) DC-only loads with sinking output wiring convention, high-speed applications

If your I/O list is DC-only and switching frequency or point density is driving the design, the 1734-OB8 or 1734-OV8 will serve better than the 1734-OW4. If you only need two relay channels, the 1734-OW2 avoids carrying two unused points in your rack. When mixed voltages, galvanic isolation, or interfaces with legacy and third-party devices are the controlling factors, the 1734-OW4 is the correct selection — check current availability at LeadTime.ca.

Expert Verdict: Is the 1734-OW4 the Right Module for Your Rack?

The Allen-Bradley 1734-OW4 fills a specific and well-defined role in POINT I/O architecture: it is the go-to relay output module for OEMs, system integrators, and plant engineers who need four isolated dry contact outputs to drive a mix of AC and DC field devices from the same compact module. The Form A normally open contacts, combined with full galvanic isolation from the POINTBus, make it the natural choice whenever grounding uncertainty, mixed load voltages, or third-party panel interfaces are present. Engineers standardizing on Allen-Bradley POINT I/O across multiple machine lines or plants benefit particularly from this module — it eliminates the need for separate interposing relay panels and keeps the architecture consistent with the rest of the distributed I/O strategy.

The 1734-OW4 has real and predictable limitations that should be stated plainly. Relay contacts have finite mechanical life, and electromechanical switching is inherently slower than solid-state. If your application runs outputs at high frequency, requires a high cycle count, or is exclusively DC, the 1734-OB8 (sourcing transistor, 8 points) or 1734-OV8 (sinking transistor, 8 points) will outlast and outperform the relay module in that duty. Similarly, the 1734-OW2 is the more efficient choice when only two relay channels are needed and rack space is at a premium. The 1734-OW4 is not a universal output module — it is the right relay output module for the right application, and specifying it outside that window creates avoidable maintenance problems.

From a procurement standpoint, the 1734-OW4 is a standard, widely catalogued POINT I/O component with established availability in North America. As a common catalogue item, it is generally accessible through specialist automation distributors with shorter lead times than allocation-sensitive or newer product lines. That said, demand spikes and factory allocation cycles can affect even standard POINT I/O parts — validating stock status before committing to a build schedule is always worth the two-minute call. View current pricing and availability for the 1734-OW4 at LeadTime.ca, where the team can also confirm compatible terminal bases and network adapters for your specific rack configuration.

For volume pricing, lead time confirmation before a production build, or help selecting between relay and transistor POINT I/O modules for your I/O list, contact the LeadTime.ca team directly — we ship worldwide.

What Engineers Need to Know Before Ordering the 1734-OW4

Forum and community searches across Reddit r/PLC, Reddit r/automation, PLCTalk, PLCS.net, MrPLC, and Rockwell Automation user forums returned no meaningful model-specific discussion threads for the 1734-OW4 or the broader POINT I/O relay output module family. That absence is itself informative: components that generate sustained online discussion are usually doing so because of a recurring problem, a confusing specification, or a well-known compatibility trap. The 1734-OW4 appears to be a routine, generally trouble-free module in most deployed systems — it does its job and does not draw complaints. When a component is this unremarkable in public discourse, the real ordering risk comes not from the module itself but from the surrounding specification decisions that are easy to get wrong quietly.

The most consequential decision point is confirming that relay outputs are actually what the application requires. In broader POINT I/O discussions across these same forums, the most frequently observed confusion is between relay, sourcing transistor, and sinking transistor output types. Engineers ordering replacement modules under time pressure, or procurement staff working from an incomplete part number, can easily land on a transistor module when a relay module is what the panel wiring demands — or vice versa. The module designations are similar enough (OW4 for relay, OB8 for sourcing transistor, OV8 for sinking transistor) that a misread under pressure is a genuine risk. Building a cross-check of output type against the panel schematic into the ordering process eliminates this class of error entirely.

The second category of pre-order risk specific to this module is the external load power requirement. Rockwell Automation documentation is explicit: the 1734-OW4 relay contacts are voltage-free, and load power cannot be drawn from the internal POINTBus. Engineers who are new to relay output modules, or who are accustomed to sourcing transistor modules where the load supply is typically provided through the module's wiring terminals in a more integrated way, sometimes arrive at commissioning without an external supply connected to the terminal base. This is not a module defect — it is a design and wiring oversight that causes non-functioning outputs and commissioning delays. Confirming external supply provision on the schematic before the panel is built is the correct prevention step. When in doubt about whether a specific rack configuration, firmware version, or terminal base combination is compatible with the 1734-OW4, a specialist distributor with POINT I/O application knowledge is the fastest path to a confident answer.

Wiring and Installation Overview

The following points summarize key installation requirements for the 1734-OW4. For complete wiring diagrams, terminal numbering, and step-by-step procedures, refer to the Rockwell Automation POINT I/O installation instructions and relay output module manual.

  • Mount the correct POINT I/O terminal base (1734-TB, 1734-TBS, 1734-TOP, or 1734-TOPS) on DIN rail and secure it before inserting the module; the base type determines the terminal arrangement and must be specified separately from the module.
  • Slide the 1734-OW4 onto the seated terminal base until the locking tab engages fully; the module draws logic power from the POINTBus through the base connection — no separate logic supply wiring is required.
  • External load power must be wired independently to the designated terminals on the base; the relay contacts are voltage-free and cannot be energized without this external supply, regardless of whether the module status LED is active.
  • Wire each load to its corresponding output terminal following the numbering in the Rockwell installation manual; verify that load voltage and worst-case inrush current for inductive loads (contactor coils, solenoid valves) are within the relay contact rating, and add external fusing and surge suppression as required by local electrical code and the manufacturer's guidance.
  • After energizing the system, check module and individual channel status LEDs to confirm the module is communicating on the POINTBus and test each relay output from the controller before connecting live field loads.

Compatible Terminal Bases and Network Adapters

The 1734-OW4 requires a separately ordered POINT I/O terminal base and integrates with any supported POINT I/O network adapter. The following components are documented as compatible:

  • 1734-TB — standard POINT I/O terminal base, screw-type wiring terminals.
  • 1734-TBS — POINT I/O terminal base with spring-clamp wiring terminals.
  • 1734-TOP — POINT I/O terminal base with cage-clamp wiring terminals, top-entry.
  • 1734-TOPS — POINT I/O terminal base with cage-clamp wiring terminals, top-entry spring.
  • EtherNet/IP, ControlNet, DeviceNet, and PROFIBUS POINT I/O network adapters — confirmed compatible with POINT I/O relay output modules when used with RSLogix or Studio 5000 at the appropriate firmware version, as documented by Rockwell Automation.

Wrong-Part Prevention Checklist Before You Order

Use the following checklist verbatim against your bill of materials and panel drawings before placing any order for the 1734-OW4:

  1. Confirm you truly need relay (dry contact) outputs, not transistor (sourcing/sinking) outputs.
  2. Verify four output points are sufficient for the machine segment; otherwise consider multiple modules or a higher-density variant.
  3. Check that load voltage and current are within the module's rating for both DC and AC, including inrush for inductive loads.
  4. Ensure you have the correct POINT I/O terminal base (1734-TB, 1734-TBS, 1734-TOP, or 1734-TOPS) already specified or ordered.
  5. Confirm your chosen network adapter (EtherNet/IP, DeviceNet, ControlNet, PROFIBUS) supports POINT I/O relay modules with your controller and firmware level.
  6. Check series compatibility and replacement strategy if mixing older POINT I/O modules (Series C module in a mixed rack).
  7. Verify panel depth, clearance, and temperature range are suitable for the module's environmental ratings.
  8. Make sure external load power is available; 1734-OW4 cannot draw load power from the internal POINTBus.

If any item on this checklist raises a question, contact the LeadTime.ca team before ordering — confirming compatibility takes minutes and prevents costly field rework.

Frequently Asked Questions

Does the 1734-OW4 supply its own load power, or must I wire an external supply?

The 1734-OW4 relay contacts are voltage-free dry contacts. Rockwell Automation documentation explicitly states that load power cannot be drawn from the internal POINTBus — an external power supply must always be wired to the terminal base to energize the connected loads. Forgetting this external supply is the most common commissioning mistake with this module.

Which POINT I/O terminal bases are compatible with the 1734-OW4?

The 1734-OW4 is compatible with four POINT I/O terminal base types: 1734-TB (screw), 1734-TBS (spring-clamp), 1734-TOP (top-entry cage-clamp), and 1734-TOPS (top-entry spring cage-clamp). The terminal base must be ordered separately and must be mounted on the DIN rail before inserting the module. Base selection affects wiring termination style but not the module's electrical performance.

Can I mix the 1734-OW4 with older POINT I/O modules in the same rack?

The 1734-OW4 is documented as Series C within the POINT I/O relay output module family. Mixing module series within a POINT I/O rack is possible in many configurations, but series compatibility and firmware requirements should be verified against your specific network adapter and controller revision before committing to a mixed rack design. Consulting Rockwell Automation's compatibility documentation or a specialist distributor is recommended when combining older and current POINT I/O hardware.

What is the right alternative if I need faster switching or DC-only outputs?

For DC-only applications requiring faster switching speed, higher cycle life, or greater point density, the 1734-OB8 (sourcing transistor, 8 points) and 1734-OV8 (sinking transistor, 8 points) are the appropriate POINT I/O alternatives to the 1734-OW4. These solid-state modules eliminate the mechanical life constraints of relay contacts and are better suited to high-frequency output applications. The relay architecture of the 1734-OW4 is the correct choice only when mixed AC/DC loads or galvanic isolation requirements are present.

How do I add the 1734-OW4 to a Studio 5000 / Logix Designer project?

The 1734-OW4 is added to the controller hardware tree by selecting the appropriate POINT I/O relay output module from the module catalog within Studio 5000 or Logix Designer. The module requires configuration of the Requested Packet Interval (RPI) and output data format appropriate for the network adapter in use. Full configuration procedures are detailed in Rockwell Automation's POINT I/O relay output module documentation and the relevant network adapter user manual.

What does the output LED status indicate on the 1734-OW4?

The 1734-OW4 provides module-level and individual channel status LED indicators. A channel LED that is active indicates the controller has commanded that output on. If the LED is active but the field device does not respond, the cause is typically an open in the external load circuit — blown external fuse, missing external supply, wiring error at the terminal base, or a load exceeding the relay contact rating. Module-level faults visible through the network adapter typically indicate a POINTBus communication issue or addressing problem rather than a relay output fault.

Why Order the 1734-OW4 Through LeadTime.ca

  • The 1734-OW4 is a standard POINT I/O catalogue item — LeadTime.ca maintains stock visibility and can confirm real availability and lead time before you commit to a build schedule.
  • Specialist application knowledge: the team can validate that the 1734-OW4 is the correct module for your rack configuration, confirm compatible terminal base part numbers, and flag potential network adapter or firmware compatibility questions.
  • If the 1734-OW4 faces allocation or extended factory lead time, LeadTime.ca can identify in-stock alternatives within the POINT I/O relay output module family and advise on compatibility.
  • Volume pricing is available for OEM builders and MRO stocking orders — contact for current pricing on multi-unit quantities.
  • LeadTime.ca ships worldwide — engineers and procurement teams in any region can source standard Allen-Bradley POINT I/O modules through a single specialist channel.

At-a-Glance Summary

  • Catalog number: Allen-Bradley 1734-OW4 — POINT I/O 4 Point Digital Output Module (4 Relay Outputs), Series C.
  • Four isolated Form A (normally open) relay contacts — voltage-free dry contacts, load power must be wired externally.
  • Supports mixed AC and DC loads within the relay contact's rated voltage and current limits.
  • Compatible terminal bases: 1734-TB, 1734-TBS, 1734-TOP, 1734-TOPS — ordered separately.
  • Works with EtherNet/IP, ControlNet, DeviceNet, and PROFIBUS POINT I/O network adapters with compatible controller and firmware.
  • Operating temperature: -20 to 55 °C; storage temperature: -40 to 85 °C; humidity: 5–95% non-condensing.
  • Best application fit: mixed-voltage loads, galvanic isolation requirements, contactor and valve switching at low to moderate frequency.
  • Not the right module for: DC-only high-speed applications (use 1734-OB8/OV8) or when only two relay channels are needed (use 1734-OW2).
  • Standard, widely catalogued POINT I/O item — check current stock status and lead time at LeadTime.ca before committing to a build schedule.

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