Allen-Bradley 1769-PA2 — CompactLogix Power Supply Buying Guide

By Abdullah Zahid
15 min read
Allen-Bradley 1769-PA2 CompactLogix AC 2A power supply module for 1769 Compact I/O rack

Allen-Bradley 1769-PA2 CompactLogix AC 2A Power Supply, 120/240 VAC Input, 2 A @ 5 VDC Output — Specs, Sizing, and Buying Guide

Controls engineers specifying or replacing power supplies for a 1769 Compact I/O rack need to confirm three things fast: input voltage compatibility, backplane current capacity, and whether this is the right variant for their system load. The Allen-Bradley 1769-PA2 is the widely used AC-input expansion power supply for 1769 Compact I/O and CompactLogix L3x/L3y systems, accepting 85–265 VAC at 47–63 Hz and delivering 2 A at 5 VDC and 1 A at 24 VDC to the 1769 backplane. If you are replacing a failed unit or designing a new I/O segment around a CompactLogix L3x controller or 1769-AENTR EtherNet/IP adapter, this is the standard catalog number you are looking for.

If you have already confirmed this is the correct part for your system, check current pricing and availability for the 1769-PA2 at LeadTime.ca — ships worldwide.

Who Should Buy the 1769-PA2 — and Who Should Not

The 1769-PA2 is the right choice for controls engineers and OEM panel designers working within an established 1769 Compact I/O or CompactLogix L3x/L3y architecture who need a reliable, AC-mains-fed backplane power supply with a proven long service record. Order it when all of the following apply to your application:

  • Your platform is 1769 Compact I/O or CompactLogix L3x/L3y — not MicroLogix 1762, 5069 Compact 5000, or ControlLogix 1756.
  • Your panel has AC mains available at 85–265 VAC, 47–63 Hz (single-phase).
  • Your documented 5 VDC and 24 VDC backplane current totals for all connected 1769 modules stay within 2 A at 5 V and 1 A at 24 V, accounting for both sides of the supply.
  • The installation environment is within 0–60 °C, Pollution Degree 2, Overvoltage Category II, and altitude up to 2000 m.
  • You are standardizing on a spare part or expansion supply across multiple CompactLogix-based machines in the same facility.

If your total 1769 backplane current exceeds the 2 A / 1 A limits, the 1769-PA4 is the correct higher-current alternative. If your panel runs on a 24 VDC bus rather than AC mains, the 1769-PB2 is the right variant. New projects migrating to newer Rockwell platforms should evaluate the 5069 Compact 5000 family instead.

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What the 1769-PA2 Actually Does in a CompactLogix System

The 1769-PA2 is not a general-purpose DIN-rail power supply. It is a bus-interface power module that mounts directly onto the 1769 I/O bus and converts single-phase AC mains to the 5 VDC logic power and 24 VDC sensor power that 1769 I/O modules and compatible CompactLogix L3x/L3y controllers consume on the backplane. Its mechanical keying and bus connector physically integrate it into the 1769 module row — it cannot be substituted with a standalone 24 VDC supply and a set of wires.

The supply distributes power in both directions from its mounting position, meaning 1769 modules can be placed to the left and right of the 1769-PA2 within the same I/O bank. Critically, it powers PLC backplane electronics and limited sensor loads only — the 1 A at 24 VDC output is not intended as a source for high-current field devices such as solenoids, contactors, or large sensor networks. For those loads, a separate external 24 VDC supply is required.

Two verified proof points frame the performance envelope: the input accepts 85–265 VAC at 47–63 Hz, covering global mains standards within a single hardware variant, and the output is rated at 2 A at 5 VDC and 1 A at 24 VDC for the 1769 backplane, as documented in Rockwell's Compact I/O power supply installation instructions. The operating envelope spans 0–60 °C in a Pollution Degree 2 industrial environment, up to an altitude of 2000 m without derating.

Where the 1769-PA2 Sits in a Typical System

The 1769-PA2 slots into the middle of the 1769 I/O bus segment, feeding backplane power to the modules on either side. Here is the typical component chain:

  • CompactLogix L3x/L3y CPU (or 1769-AENTR EtherNet/IP adapter for remote I/O) — provides program execution or network connectivity and draws a portion of backplane current from the supply.
  • 1769-PA2 — mounts adjacent to the CPU or adapter, supplying 2 A at 5 V and 1 A at 24 V along the bus in both directions.
  • 1769 digital and analog I/O modules — mounted to the left and/or right of the 1769-PA2, consuming 5 VDC logic power and 24 VDC sensor power from the backplane.
  • 1769 end caps and bus terminators — required at both ends of the I/O bank to complete the bus connection mechanically and electrically.
  • External 24 VDC power supply — provides field-side power for output loads, solenoids, and high-current sensors that exceed the 1 A backplane 24 V budget.

Industries and Applications That Rely on the 1769-PA2

The 1769-PA2 is most commonly specified in small-to-medium machine control panels built around CompactLogix L3x/L3y controllers. Packaging machine OEMs use it to power 1769 I/O banks for conveyor controls, reject systems, and date-coding stations. Automotive and discrete manufacturing integrators fit it into machine cells for assembly line control and fixture I/O. Food and beverage facilities specify it for filling lines and palletizers where a Compact I/O architecture is already standardized.

In process applications, the 1769-PA2 appears on small water and wastewater pump stations, building automation skids, and process control panels using CompactLogix as the local controller. Remote I/O applications using the 1769-AENTR EtherNet/IP adapter are a particularly common deployment — the adapter serves as the bus head, and the 1769-PA2 supplies the downstream 1769 I/O modules at the remote panel without requiring a full CPU on site.

Maintenance and MRO teams also specify the 1769-PA2 as a stocked spare across multi-machine plants to reduce mean time to repair on critical lines where downtime costs are high.

Application Typical Deployment
Packaging machine control CompactLogix L3x CPU with 1769 digital I/O modules, 1769-PA2 as primary bus supply
Remote I/O panel (EtherNet/IP) 1769-AENTR adapter with downstream 1769 I/O bank powered by 1769-PA2
Automotive assembly cell Compact I/O rack with mixed analog/digital modules, 1769-PA2 sized to 2 A / 1 A load budget
Water/wastewater pump station CompactLogix L3x with small 1769 I/O bank, 1769-PA2 as sole bus power source
OEM machinery spare part standardization 1769-PA2 kept as a stocked spare across multiple identical machines in a facility
I/O expansion segment Second 1769-PA2 added to extend an existing 1769 bank when CPU-integrated power is insufficient

Electrical and Mechanical Specifications at a Glance

Parameter Value
Input voltage range 85–265 VAC, 47–63 Hz (single-phase AC)
Nominal input 120 / 240 VAC (selector switch setting)
Output — 5 VDC 2 A (1769 backplane logic power)
Output — 24 VDC 1 A (1769 backplane / limited sensor power)
Operating temperature 0–60 °C (32–140 °F)
Altitude (no derating) Up to 2000 m
Pollution degree / OV category Pollution Degree 2, Overvoltage Category II
Mounting DIN rail or panel mount (open-style)
Dimensions (H x W x D) Approx. 4.65 in x 2.76 in x 3.43 in
Status indication Front-panel status LEDs

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

1769-PA2 vs 1769-PA4 vs 1769-PB2: Which Variant Do You Actually Need?

The 1769 power supply family offers AC-input and DC-input variants at two current levels. Choosing the wrong catalog number at the design stage is the single most common ordering mistake engineers make with this product line.

Model Input Type 5 VDC Output 24 VDC Output Best Used When
1769-PA2 85–265 VAC, 47–63 Hz 2 A 1 A AC mains available; small-to-medium 1769 I/O load
1769-PA4 85–265 VAC, 47–63 Hz 4 A 2 A AC mains available; higher-density I/O or specialty modules exceed 1769-PA2 limits
1769-PB2 24 VDC input 2 A 1 A Panel bus is 24 VDC; no AC mains in enclosure
1769-PS120 120 VAC — — Specific 120 VAC-only applications; confirm suitability with Rockwell documentation

If your total 1769 backplane load exceeds 2 A at 5 V or 1 A at 24 V, the 1769-PA4 is the correct upgrade path — check current availability for both variants at LeadTime.ca before finalizing your bill of materials.

Expert Verdict: Is the 1769-PA2 the Right Power Supply for Your Rack?

The 1769-PA2 has earned its position as the default AC-input power supply for CompactLogix L3x/L3y and 1769-AENTR-based systems by being straightforward to integrate and dependable in service when properly sized. It is the right part for controls engineers and OEM panel designers who are working within an established 1769 Compact I/O architecture, have AC mains available in the panel, and whose documented backplane current totals fit comfortably within 2 A at 5 VDC and 1 A at 24 VDC. The community consensus of long service life and quick swap-out on failure reflects genuine reliability — when the hardware is correctly specified, it rarely becomes the weak point in a system. The wide AC input range of 85–265 VAC at 47–63 Hz also means a single part number covers most global mains standards, simplifying international OEM standardization.

The 1769-PA2 has real limits that matter in specific scenarios. Engineers specifying higher-density 1769 racks with multiple analog, specialty, or high-draw I/O modules will quickly exhaust the 2 A at 5 V budget and should move to the 1769-PA4 without hesitation. If the panel infrastructure is built around a 24 VDC bus rather than AC mains, the 1769-PB2 is the correct catalog number — ordering a 1769-PA2 in that situation is a wiring problem, not just a specification mismatch. And for new projects starting from a clean sheet, it is worth evaluating whether the 5069 Compact 5000 family better serves the long-term platform roadmap before locking in another generation of 1769 hardware investment.

From a procurement standpoint, the 1769-PA2 is a well-stocked part in the North American distribution channel, with typical single-unit availability from specialist distributors. For critical production lines, keeping at least one unit as a plant spare is a straightforward insurance policy given the cost of downtime. Pricing is available on the product page, and lead times can shift with demand — confirming stock before committing to a build schedule is always worth the five-minute check. If you are ready to confirm availability, view current pricing and stock for the 1769-PA2 at LeadTime.ca.

For volume pricing, project quantities, or to verify lead time before a production build, contact the LeadTime.ca team directly — we source and ship worldwide.

What Engineers Need to Know Before Ordering the 1769-PA2

Community feedback from forums including PLCTalk, PLCS.net, MrPLC, and Reddit's automation communities paints a consistent picture: the 1769-PA2 is widely regarded as a reliable, set-and-forget component in CompactLogix systems. Engineers with years of field experience describe it as a module that integrates directly into existing 1769 racks without custom wiring, and maintenance staff appreciate the standardized form factor that makes a swap-out quick when a unit does fail. The volume of positive sentiment around long service life reflects what the specifications suggest — when the supply is correctly sized and the selector switch is properly set, it is rarely a source of system problems.

Where the community consistently raises concerns is at the intersection of sizing and assumptions. Threads across multiple forums repeatedly surface confusion about how many 1769 modules a single 1769-PA2 can reliably support — particularly when a mix of analog, specialty, or high-draw digital modules is involved. The 2 A at 5 VDC and 1 A at 24 VDC limits require a real, module-by-module current tally rather than a rough headcount. Engineers who skip a formal power budget often discover mid-commissioning that they needed a 1769-PA4. The cost comparison to generic DIN-rail 24 VDC supplies also comes up frequently — buyers sometimes balk at the price before understanding that a generic supply cannot substitute for a bus-interface power module with the correct mechanical and electrical backplane connection.

The 120/240 V selector switch is the single most flagged commissioning risk in community discussions. Leaving the switch in its factory default position without verifying it matches the actual mains voltage has caused startup problems and, in some cases, concern about hardware damage. This is not a complex check — but it requires an explicit step on the commissioning checklist, not an assumption. When community data on a specific part is sparse, the right response is to consult a specialist distributor who can cross-reference your I/O list against the power budget limits and confirm which variant ships from stock. LeadTime.ca's team handles exactly these pre-order verification questions for engineers sourcing 1769 components from anywhere in the world.

Wiring and Installation Overview

The following points summarize the key installation requirements for the 1769-PA2. For full wiring diagrams, terminal specifications, and step-by-step procedures, refer to the Rockwell Automation installation instructions for the 1769 power supply family.

  • Mount on DIN rail or panel in the correct orientation, with sufficient spacing and ventilation to maintain ambient temperature within 0–60 °C at the module surface.
  • Set the 120/240 V selector switch to match the actual site mains voltage before connecting AC input — verify this step physically and document it on the commissioning record.
  • Wire the AC input (L, N, and protective earth) using conductor sizes specified in the installation instructions, and protect the AC feed with external overcurrent protection devices as required by applicable electrical codes.
  • Attach 1769 I/O modules and the CPU or 1769-AENTR adapter to the right and/or left of the 1769-PA2 with bus connectors fully seated; install end caps at both ends of the I/O bank as required.
  • On initial energization, verify front-panel status LEDs indicate normal operation and confirm that modules on both sides of the supply are powered correctly before proceeding with I/O checkout.

Compatible 1769 System Components

The 1769-PA2 is specified as part of a broader 1769 Compact I/O and CompactLogix system. The following components are part of the same platform and are commonly used alongside it:

  • CompactLogix L3x/L3y controllers — the primary CPUs the 1769-PA2 was designed to support on the 1769 I/O bus.
  • 1769-AENTR EtherNet/IP adapter — used as the bus head for remote 1769 I/O panels, with the 1769-PA2 supplying backplane power to the downstream I/O modules.
  • 1769 digital and analog I/O modules — any 1769-series I/O module draws 5 VDC and 24 VDC from the bus; current draw for each must be included in the power budget against the 2 A / 1 A limits.
  • 1769-PA4 — the higher-current AC-input alternative delivering 4 A at 5 VDC and 2 A at 24 VDC for larger I/O banks.
  • 1769-PB2 — the 24 VDC-input alternative at the same 2 A / 1 A output level for DC-bus panel designs.
  • 1769 end caps and bus terminators — required at both ends of every 1769 I/O bank; must be included in the bill of materials.

Wrong-Part Prevention Checklist

Before finalizing your purchase order for the 1769-PA2, confirm every item on this checklist. Each point represents a real ordering mistake documented in engineering forums and distributor return records:

  1. Confirm the PLC/I/O platform is 1769 Compact I/O / CompactLogix (not MicroLogix 1762, 5069 Compact 5000, ControlLogix 1756, etc.).
  2. Confirm available input is AC (85–265 VAC, 47–63 Hz); do not order 1769-PA2 if only DC power is available.
  3. Confirm required backplane current (5 VDC and 24 VDC) for all 1769 modules on both sides is within 2 A @ 5 V and 1 A @ 24 V limits.
  4. Check if you need a higher-current 1769-PA4, or additional expansion power supplies, for long I/O trains or high-load specialty modules.
  5. Ensure the 120/240 V selector switch position matches the actual mains voltage before energizing.
  6. Verify mounting space and orientation for DIN rail or panel mount and that the environment meets 0–60 °C and industrial pollution degree requirements.
  7. Confirm that separate external 24 VDC supplies are provided for high-current field loads; the 1769-PA2 is sized primarily for backplane and limited sensor loads.
  8. Include required end caps/terminators and interconnecting 1769 I/O modules in the bill of material.

If you have completed this checklist and confirmed the 1769-PA2 is the correct part, check current stock and pricing at LeadTime.ca — or contact the team if you need a power budget review before ordering.

Frequently Asked Questions

How do I calculate whether the 1769-PA2 has enough capacity for my 1769 rack?

List every 1769 module — including the CPU or 1769-AENTR adapter — and record the 5 VDC and 24 VDC current draw for each from the respective module datasheets. Sum the 5 V and 24 V draws separately for all modules that will be powered by the 1769-PA2, accounting for modules on both the left and right sides of the supply. If either total exceeds 2 A at 5 V or 1 A at 24 V, the 1769-PA2 is undersized and you should evaluate the 1769-PA4 or add a second power supply. Document this power budget and keep it with your project files.

Can the 1769-PA2 power field devices like solenoids or large sensor networks?

No. The 1 A at 24 VDC output of the 1769-PA2 is intended for 1769 backplane electronics and limited low-current sensor loads only. High-current field devices — solenoids, contactors, large sensor arrays — require a separate external 24 VDC supply. Attempting to power significant field loads from the backplane 24 V bus risks overloading the supply and causing I/O errors or supply failure.

What happens if the 120/240 V selector switch is set to the wrong position?

Setting the selector switch to a voltage that does not match the actual mains supply can result in improper operation at minimum, and potential hardware damage in worst-case scenarios. This is a recurring commissioning mistake flagged across multiple engineering communities. Always verify and physically confirm the selector switch position against the actual mains voltage before energizing the panel, and record the verified setting in the commissioning documentation.

Can I use multiple 1769 power supplies in one 1769 I/O system, and how should I place them?

Yes. The 1769 architecture supports multiple power supplies in a single I/O bank. Each supply distributes power to the 1769 modules adjacent to it on both sides, subject to the per-supply current limits and the 1769 bus distribution rules defined in Rockwell's documentation. Placement matters — high-current-draw modules should be positioned close to the supply that serves them. Refer to the current Rockwell 1769 Compact I/O power supply installation instructions for the specific bus current limits and placement guidance applicable to your configuration.

What are the typical signs of a failing 1769-PA2, and how do I isolate the fault?

Common indicators include I/O modules losing power, the CompactLogix CPU reporting I/O faults on affected modules, or front-panel status LEDs indicating an abnormal state. To isolate whether the 1769-PA2 is the cause, de-energize the panel, verify the input wiring and selector switch setting, then re-energize with downstream modules disconnected one at a time to determine if a specific module is overloading the supply. If the supply remains in fault with minimal load and correct wiring, substituting a known-good 1769-PA2 is the most direct confirmation step.

Why Order the 1769-PA2 from LeadTime.ca

  • LeadTime.ca stocks and sources Allen-Bradley 1769 Compact I/O components and ships to customers worldwide — no geographic restriction on orders.
  • The team can cross-check your 1769 power budget and confirm you have the right variant — PA2, PA4, or PB2 — before the order ships.
  • Volume pricing and project quantities are available; contact the team directly for multi-unit or blanket order inquiries.
  • Hard-to-find and short-lead-time Rockwell parts are a core sourcing capability — useful when production schedules cannot wait on standard distribution lead times.
  • View the 1769-PA2 product page | Contact LeadTime.ca for a quote

At-a-Glance Summary

  • The Allen-Bradley 1769-PA2 is an AC-input 1769 Compact I/O backplane power supply delivering 2 A at 5 VDC and 1 A at 24 VDC.
  • Input accepts 85–265 VAC at 47–63 Hz — a single part number covers most global mains standards.
  • Nominal input is 120/240 VAC, selected by an onboard selector switch that must be verified before energizing.
  • Compatible with 1769 Compact I/O, CompactLogix L3x/L3y controllers, and 1769-AENTR EtherNet/IP adapter-based remote I/O racks.
  • Operating temperature range is 0–60 °C, Pollution Degree 2, Overvoltage Category II, altitude up to 2000 m without derating.
  • Dimensions are approximately 4.65 in x 2.76 in x 3.43 in; DIN rail or panel mount.
  • Upgrade to 1769-PA4 (4 A / 2 A AC input) if backplane current budget exceeds the 1769-PA2 limits; choose 1769-PB2 if only DC input is available.
  • A documented 5 V and 24 V power budget for all connected 1769 modules is the single most important pre-order step.
  • End caps and bus terminators must be included in every 1769 I/O bank bill of materials.

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