Siemens 6ES7138-4CA01-0AA0 — ET 200S Power Module Buying Guide

By Abdullah Zahid
12 min read
Siemens 6ES7138-4CA01-0AA0 PM-E 24V DC power module for ET 200S distributed I/O station in industrial automation panel

SIMATIC DP, PM-E Power Module for ET 200S; 24 V DC with Diagnostics — Siemens 6ES7138-4CA01-0AA0 Specifications, Expert Review & Alternatives

Controls engineers replacing a failed ET 200S power module or commissioning a new distributed I/O station need one answer fast: does the Siemens 6ES7138-4CA01-0AA0 match the 24 VDC architecture and 10 A load budget in front of them? This is a bottom-of-funnel decision — the SIMATIC DP ecosystem is already confirmed, and the remaining question is whether this specific PM-E power module covers the current capacity, isolation rating, and form factor of the ET 200S station at hand. At 81 mm × 15 mm × 52 mm and a 500 V DC isolation barrier between backplane bus and load voltage, the 6ES7138-4CA01-0AA0 is the current production variant of this power module, carrying a spare part designation that confirms long-term Siemens support.

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

Who Should Buy the Siemens 6ES7138-4CA01-0AA0 — and Who Shouldn't

This module is the correct choice when all of the following apply to your application:

  • Your supply voltage is exactly 24 VDC — this module is not configurable for 12 VDC, 48 VDC, or any AC voltage.
  • The total steady-state current draw of all connected I/O modules does not exceed 10 A at up to 60 °C ambient.
  • Your installation uses a standard ET 200S terminal station with a matching 81 mm × 15 mm × 52 mm module footprint.
  • You require 500 V DC galvanic isolation between backplane bus and field load voltage — a hard requirement for compliance documentation in safety-critical OEM designs.
  • You need onboard LED diagnostics (green PWR and red SF indicators) to reduce commissioning troubleshooting time without external diagnostic hardware.
  • You are replacing the discontinued 6ES7138-4CA00-0AA0 predecessor and need a confirmed drop-in substitute with identical pinout.

If your system requires a different supply voltage, if total I/O current demand exceeds 10 A per station, or if you are migrating to a PROFINET-based platform such as ET 200SP, this module is not the right fit — the variant comparison section below covers those alternatives with specific part numbers.

On this page:

What the Siemens 6ES7138-4CA01-0AA0 Actually Does in an ET 200S Station

The 6ES7138-4CA01-0AA0 is the PM-E power module within the SIMATIC DP / ET 200S distributed I/O family. Its role is specific: it is the primary power distribution point for an ET 200S terminal station, accepting 24 VDC from an upstream supply and delivering that voltage — via the backplane bus — to all I/O modules seated in the same station. Without this module, an ET 200S station has no internal power rail and none of its I/O modules can operate.

Two features distinguish this module from a passive terminal block. First, it provides 500 V DC galvanic isolation between the backplane bus and the load voltage side, which means a fault on the field wiring side cannot propagate to the PROFIBUS DP backplane and damage the controller. Second, it includes active diagnostics: a green PWR LED confirms 24 VDC is present and stable, and a red SF group error LED illuminates automatically when missing load voltage is detected — no configuration required. Reverse polarity protection is built in, preventing immediate module failure if a technician swaps the L+ and M terminals during initial wiring. The module draws only 4 mA at no load, making its quiescent power consumption negligible across multi-station designs. Power loss under full operation is 0.1 W, which keeps thermal loading in dense control panels minimal.

One constraint must be understood before ordering: the 6ES7138-4CA01-0AA0 has no internal short-circuit protection. An external C-curve circuit breaker rated at or above 10 A must be provisioned upstream. This is not optional — without it, a shorted output will destroy the module.

Where This Module Sits in a Typical SIMATIC DP System

The 6ES7138-4CA01-0AA0 occupies the power entry position in an ET 200S terminal station, sitting between the upstream 24 VDC supply and every I/O module in that station. Understanding this chain is essential for correct system design and troubleshooting.

  • PLC or DP master controller (e.g., Siemens S7-300 or S7-400) communicates over PROFIBUS DP to each ET 200S interface module in the field.
  • The ET 200S interface module (IM 151) handles PROFIBUS DP communication and passes I/O data to and from the backplane bus.
  • The 6ES7138-4CA01-0AA0 PM-E power module mounts adjacent to the IM 151 and injects 24 VDC onto the backplane bus, supplying all downstream I/O modules in that station.
  • Digital input, digital output, analog input, and analog output modules connect to the backplane downstream of the power module, drawing their operating voltage from the backplane rail the 6ES7138-4CA01-0AA0 sustains.
  • Field devices — sensors, solenoid valves, actuators — connect to the I/O module terminals; the 500 V DC isolation ensures field-side faults stay isolated from the backplane.

Industries and Use Cases That Depend on This Module

In discrete manufacturing environments, the 6ES7138-4CA01-0AA0 is most commonly found powering ET 200S stations on beverage filling lines, capping stations, and palletizing systems where a 10 A budget comfortably covers six to eight digital I/O modules per station. Automotive assembly lines use it to distribute power to proximity sensors, pressure transducers, and cylinder position feedback modules scattered across the line — the compact 15 mm width allows dense station layouts in panel space constrained by machine architecture.

Pharmaceutical dosing and labeling lines rely on this module when they need to document electrical isolation for compliance purposes — the 500 V DC isolation figure maps directly to IEC 61131-2 requirements, simplifying compliance documentation for OEM equipment designers. Food and beverage packaging OEMs building multi-station test fixtures specify the 6ES7138-4CA01-0AA0 because each station receives its own isolated power domain, preventing a field wiring fault on one station from cascading to adjacent stations.

Maintenance and plant engineering teams reach for this part most often in a failure-replacement context: a 10- to 15-year-old ET 200S installation goes offline, the failed module is pulled, and the team needs a confirmed spare with the same pinout and electrical ratings. The spare part designation Siemens assigns to the 6ES7138-4CA01-0AA0 addresses exactly this scenario — it signals that Siemens intends to keep this part available beyond the standard product lifecycle.

Application Typical Deployment
Beverage filling and capping lines One PM-E module per ET 200S station; 6–8 digital I/O modules per station
Automotive assembly distributed sensing Multiple ET 200S stations along conveyor; each with 6ES7138-4CA01-0AA0 providing isolated 24 VDC
Pharmaceutical dosing and labeling OEM 500 V DC isolation documented for electrical compliance; station-level fault containment
Legacy ET 200S failure replacement Drop-in replacement for failed power module; restores station in under 30 minutes
Greenfield packaging line with 6× ET 200S stations Six individual PM-E modules, one per station; each independently fused with C-curve breaker
Water treatment pump and valve sequencing Distributed I/O at valve islands; isolated power prevents field ground faults from reaching backplane

Electrical and Physical Specifications at a Glance

Parameter Specification
Supply Voltage 24 V DC (rated value; not configurable)
Current Carrying Capacity 10 A maximum (up to 60 °C ambient)
Input Current (No Load) 4 mA maximum
Power Loss 0.1 W typical
Voltage Isolation 500 V DC (between load voltage L+ and backplane bus)
Short-Circuit Protection None — external C-curve circuit breaker required upstream
Reverse Polarity Protection Yes — built in
Dimensions (H × W × D) 81 mm × 15 mm × 52 mm
Weight Approximately 35 g
Operating Temperature 0–60 °C

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

6ES7138-4CA01-0AA0 vs. Predecessor, ET 200SP, and PROFINET Alternatives

Model Voltage Current Platform Isolation Status Notes
6ES7138-4CA01-0AA0 24 V DC 10 A ET 200S / SIMATIC DP 500 V DC Current production — spare part Correct part for all ET 200S 24 VDC stations
6ES7138-4CA00-0AA0 24 V DC 10 A ET 200S / SIMATIC DP 500 V DC Discontinued / end-of-life Identical pinout; order 4CA01 for replacements
6ES7138-6KA01-0BA0 24 V DC 10 A (model-dependent) ET 200SP Per ET 200SP spec Current production Not pin-compatible; full station redesign required
ET 200 Eco PN power supply 24 V DC Varies by model PROFINET Per model spec Current production Requires PROFINET-capable PLC; not a drop-in swap
External 24 VDC supply (standalone) 24 V DC 10–20 A typical N/A — panel mount None (no backplane isolation) Available Does not replace PM-E; ET 200S still needs internal power module

If your existing installation uses ET 200S and your supply is 24 VDC, the 6ES7138-4CA01-0AA0 is the correct and only current-production choice — check current availability at LeadTime.ca.

Expert Verdict: When to Buy This Module and When to Walk Away

The 6ES7138-4CA01-0AA0 does exactly what it is designed to do, and does it well: it delivers stable, isolated 24 VDC power to an ET 200S station with onboard diagnostics that meaningfully reduce commissioning and troubleshooting time. The 500 V DC isolation between field load and backplane bus is a genuine engineering asset — it contains field-side wiring faults at the station level, which matters on long production lines where a single wiring error should not shut down an entire PROFIBUS DP segment. The 15 mm width and 35 g weight make it practical to stack multiple stations in panels where space is already at a premium. For any engineer maintaining or expanding a SIMATIC DP / ET 200S installation with a 24 VDC cabinet architecture, this is the right module and there is no equivalent alternative within the ET 200S product family.

The honest limits are equally worth stating. The 10 A ceiling is a hard constraint — it is not derated for future growth headroom in stations already drawing 9 A, and there is no higher-current variant of the PM-E in the same form factor. Engineers planning stations with high-current output modules or a large number of analog modules should audit the full current budget before ordering. The absence of internal short-circuit protection is a notable gap compared to some competing distributed I/O power modules; the C-curve external breaker requirement adds a panel design step that occasionally gets overlooked. And if your broader control system roadmap involves migrating to PROFINET within the next two to three years, the 6ES7138-4CA01-0AA0 is the right repair-and-maintain choice now but not the foundation for a greenfield design — ET 200SP is a more future-aligned platform for new builds.

From a procurement standpoint, the spare part designation is favorable: Siemens maintains production availability, and major industrial distributors typically carry stock for 2–5 day delivery. If a unit is out of stock, factory lead time can reach 8–10 weeks, which makes keeping one spare on the shelf a reasonable policy for facilities where this module is deployed across multiple stations. Warranty terms differ by source — 2 years from some distributors, 12 months from others, and 6 months on refurbished units — so confirm terms before ordering refurbished stock for mission-critical applications. If this matches your system requirements, view current stock and pricing at LeadTime.ca.

For volume pricing or to confirm lead time before committing to a build, contact the LeadTime.ca team directly — we ship worldwide.

Wiring and Installation Overview

  • Connect 24 VDC positive (L+) and negative/ground (M) to the module input terminals; confirm polarity before applying power — reverse polarity protection prevents module damage but will prevent operation until polarity is corrected.
  • Install an external C-curve circuit breaker rated at or above 10 A on the positive supply line upstream of the module; this is mandatory and not substitutable with a T-curve or D-curve device given inductive load starting currents.
  • Seat the module onto the ET 200S DIN rail backplane with the connector fully engaged before applying power; partial seating is a common cause of false SF diagnostics on initial commissioning.
  • After power-up, the green PWR LED should illuminate within approximately 1 second; a red SF LED at this stage indicates missing load voltage — check the upstream breaker and supply voltage before proceeding.
  • Verify operating environment is within 0–60 °C ambient; do not mount adjacent to heat sources exceeding this range, and confirm no condensation risk in the panel before closing up.

What Engineers Get Wrong When Ordering This Part

Before placing your order, work through this verbatim checklist drawn from field experience and distributor returns data. Each item represents a real ordering or installation error that results in the wrong part being installed or a module being damaged on first power-up:

  1. Verify incoming supply voltage is exactly 24 VDC (not 230 VAC three-phase or 48 VDC).
  2. Confirm ET 200S base unit frame size matches this power module (standard ET 200S is the primary host).
  3. Check current draw of all connected I/O modules does not exceed 10 A steady-state plus inrush.
  4. Ensure external circuit breaker with C-curve characteristic is provisioned upstream (module has no internal short-circuit protection).
  5. Confirm DIN rail mounting or terminal layout matches ET 200S backplane connector pinout.
  6. Verify operating temperature of installation environment is 0–60 °C (typical industrial range); do not install in freezer or furnace-adjacent cabinets.
  7. Check that replacement order specifies exact model 6ES7138-4CA01-0AA0, not the discontinued 6ES7138-4CA00-0AA0 predecessor.
  8. Confirm this is a SPARE PART (not OEM bundled); spare parts have longer lead times and may require obsolescence clearance.

If any item on this checklist raises a question about fit, contact the LeadTime.ca team before ordering — we can confirm compatibility and stock status before you commit.

Frequently Asked Questions

Can I use the 6ES7138-4CA01-0AA0 with a 48 VDC supply?

No. The module is rated 24 V DC only. Applying 48 VDC will damage the module and void any warranty. If your cabinet architecture uses 48 VDC distribution, a different power module designed for that voltage class is required — the 6ES7138-4CA01-0AA0 cannot be configured or adapted for any other supply voltage.

What is the actual difference between the 6ES7138-4CA01-0AA0 and the discontinued 6ES7138-4CA00-0AA0?

Electrically and mechanically, the specifications are identical — same 24 VDC rating, same 10 A capacity, same 500 V DC isolation, and same pinout. The 4CA00 is end-of-life and no longer in production; the 4CA01 is the current production spare part. Both are pin-compatible, so the 4CA01 is a confirmed drop-in replacement for any system currently running the 4CA00.

Does this module include a fuse or short-circuit protection?

No. The 6ES7138-4CA01-0AA0 includes reverse polarity protection but has no internal short-circuit protection — no solid-state fuse, no magnetic breaker. An external C-curve circuit breaker must be installed upstream on the positive supply line. Without it, a shorted output will destroy the module. This is a design requirement, not a workaround.

How much current does this module draw from the 24 VDC supply at no load?

At no load, input current is 4 mA maximum. Under full 10 A output load, input current will be approximately 10.5 A when accounting for the 0.1 W module power loss. Both figures are low enough that this module does not meaningfully affect the sizing calculation for the upstream 24 VDC supply in most station designs.

Can one 6ES7138-4CA01-0AA0 power multiple ET 200S stations?

No. Each ET 200S terminal station requires its own PM-E power module. The module feeds the backplane of a single station; it is not designed to be shared between stations or daisy-chained. Installing one module for multiple stations will result in insufficient power distribution and diagnostic errors.

Is the 6ES7138-4CA01-0AA0 considered obsolete?

No. Siemens designates it as a spare part, which signals an intent to maintain production availability beyond the standard product lifecycle. However, its predecessor — the 6ES7138-4CA00-0AA0 — is obsolete. Always confirm you are ordering the 4CA01 variant, not the 4CA00, when placing replacement orders.

Why Source the 6ES7138-4CA01-0AA0 from LeadTime.ca

  • LeadTime.ca ships the Siemens 6ES7138-4CA01-0AA0 worldwide — no geographic restriction on orders.
  • Stock status and lead time are confirmed before orders are placed, which matters when a production line is waiting on a single power module.
  • Volume pricing is available for multi-unit orders — contact the team directly for OEM and MRO quantity tiers.
  • Hard-to-find spare parts and discontinued predecessors can often be sourced through LeadTime.ca's distributor network when primary channels show extended backorder.
  • The team can verify compatibility against your ET 200S station configuration before you commit to an order.

At-a-Glance Summary

  • Official product name: SIMATIC DP, PM-E Power Module for ET 200S; 24 V DC with Diagnostics
  • Catalog number: 6ES7138-4CA01-0AA0 — current production, spare part designation
  • Supply voltage: 24 V DC rated — no other voltage class supported
  • Current carrying capacity: 10 A maximum at up to 60 °C ambient
  • Isolation: 500 V DC between load voltage and backplane bus
  • Input current at no load: 4 mA maximum; power loss 0.1 W typical
  • Dimensions: 81 mm × 15 mm × 52 mm; weight approximately 35 g
  • Diagnostics: green PWR LED (power present), red SF LED (missing load voltage); 3 byte parameter
  • Reverse polarity protection: built in — short-circuit protection: not included; external C-curve breaker required
  • Operating temperature: 0–60 °C
  • Predecessor 6ES7138-4CA00-0AA0 is discontinued; 6ES7138-4CA01-0AA0 is the confirmed drop-in replacement with identical pinout
  • Typical distributor lead time: 2–5 days in stock; 8–10 weeks from factory if out of stock