Siemens 6ES7138-4FA02-0AB0 Retrofit-Compatible Power Module

Siemens 6ES7138-4FA02-0AB0 Retrofit-Compatible Power Module for Legacy ET 200S Systems

The Siemens 6ES7138-4FA02-0AB0 is a power module designed for the ET 200S distributed I/O system, widely deployed across manufacturing plants, process automation lines, and legacy control cabinets worldwide. As original production of this module has been discontinued or supply has become constrained, many automation engineers and maintenance teams are actively seeking verified retrofit-compatible replacements that can be installed with minimal disruption to existing panel layouts, terminal wiring, and PLC program logic.

At NINERMAS, we specialize in sourcing, testing, and supplying hard-to-find industrial control components including the 6ES7138-4FA02-0AB0. Every unit we ship undergoes functional verification prior to dispatch, and is backed by a 12-month warranty. Whether you are managing a planned upgrade or responding to an unplanned failure, our inventory is maintained to support fast turnaround for critical production environments.

Upgrade Compatibility Table

Retrofit Planning for Existing Automation Systems

When integrating the 6ES7138-4FA02-0AB0 into an existing ET 200S station, the retrofit process typically begins with a thorough audit of the current power distribution architecture within the control cabinet. Engineers must confirm that the upstream 24 V DC supply — often sourced from a SITOP PSU100S or equivalent Siemens power supply unit — can sustain the combined load of all active I/O modules on the same power segment. Insufficient power headroom is one of the most common causes of intermittent faults after a module swap.

The terminal module associated with the 6ES7138-4FA02-0AB0 must be inspected for wear, particularly on the blade contacts and locking mechanism. In many legacy installations, the terminal module itself — such as the 6ES7193-4CA40-0AA0 — may need to be replaced simultaneously to ensure reliable contact. Technicians should also verify that the DIN rail mounting position and available slot width in the existing rack are compatible with the replacement module’s physical footprint before committing to installation.

For stations that include digital input modules such as the 6ES7131-4BF00-0AA0 or analog input modules like the 6ES7134-4FB01-0AB0, the power module’s load current capacity must be recalculated to account for all downstream consumers on the same power segment. Where I/O expansion is planned as part of the retrofit, additional power modules may be required to segment the load appropriately across the ET 200S station.

Communication continuity is another critical consideration. The ET 200S interface module — typically an IM 151-1 variant such as the 6ES7151-1AA05-0AB0 — must remain operational throughout the swap. In PROFIBUS DP environments, the bus address and baud rate settings stored in the IM module are preserved independently of the power module, which simplifies hot-swap planning. In PROFINET configurations, the device name and IP address assignment should be documented before any hardware change is initiated.

Where the retrofit is part of a broader migration from PROFIBUS to PROFINET, the replacement of the power module often coincides with the introduction of a new IM 151-3 PN interface module and associated reconfiguration of the HMI communication links. Operators should ensure that any SIMATIC HMI TP700 Comfort or similar panel screens referencing ET 200S I/O tags are updated to reflect any address changes introduced during the migration. Program blocks in STEP 7 or TIA Portal that reference the affected I/O modules should be reviewed and, where necessary, recompiled and downloaded to the CPU 315-2 DP or equivalent controller.

Signal isolation requirements should also be assessed during retrofit planning. In environments with high electrical noise — such as those involving variable frequency drives or large motor starters — the addition of a 6ES7138-4CA01-0AA0 signal isolator or equivalent barrier module may be advisable to protect the integrity of analog signals passing through the upgraded station. Proper cable shielding and grounding practices should be verified at the same time.

Downtime Control During System Migration

Minimizing production downtime during a power module replacement on an ET 200S station requires careful pre-staging and a disciplined change management process. Before the maintenance window begins, the existing PLC program should be backed up in full — including all data blocks, function blocks, and hardware configuration files — using STEP 7 or TIA Portal. A copy of the current hardware configuration, including the slot assignments and module parameters for the affected ET 200S station, should be exported and stored offline.

Where the production schedule permits, a parallel test bench using a spare ET 200S rack and a programming cable such as the 6ES7972-0CB20-0XA0 PC Adapter USB can be used to validate the replacement module’s behavior before it is installed in the live system. This approach allows engineers to confirm that the module powers up correctly, that the green LED indicators on both the power module and the IM interface module illuminate as expected, and that the CPU recognizes the station without generating hardware fault OBs.

During the live swap, the affected power segment should be de-energized in a controlled sequence, with the 24 V DC supply isolated at the cabinet’s terminal block rather than at the module itself. After the replacement module is seated and the terminal module locking tab is engaged, power should be restored incrementally, with the CPU placed in STOP mode initially to allow the hardware configuration to be verified before resuming automatic control. Field instruments connected to the I/O modules on the affected segment should be monitored for correct signal levels before the CPU is returned to RUN mode.

By following a structured pre-commissioning checklist — covering power capacity, terminal integrity, module addressing, program compatibility, HMI tag mapping, communication link verification, and physical installation clearances — most ET 200S power module replacements can be completed within a planned maintenance window of two to four hours, with no permanent loss of program logic or process data.

Retrofit Support FAQ

Q1: Is the 6ES7138-4FA02-0AB0 a direct drop-in replacement for earlier PM-E variants in the ET 200S series?
In most cases, yes. The 6ES7138-4FA02-0AB0 is mechanically and electrically compatible with earlier PM-E variants including the 6ES7138-4FA01-0AB0 and 6ES7138-4FA00-0AB0, provided the associated terminal module is in good condition. Engineers should confirm the hardware configuration in STEP 7 or TIA Portal reflects the correct module order number to avoid diagnostic warnings.

Q2: What commissioning steps are required after installing the replacement module?
After physical installation, the CPU should be placed in STOP mode and the hardware configuration downloaded to confirm the new module is recognized. The power LED on the module and the SF/BF LEDs on the IM interface module should be checked. Any pending hardware fault OBs should be cleared before returning the CPU to RUN mode. Terminal wiring torque should be verified to manufacturer specification.

Q3: Does NINERMAS test units before shipment, and what warranty is provided?
Yes. All units supplied by NINERMAS are functionally tested prior to dispatch. Each 6ES7138-4FA02-0AB0 is covered by a 12-month warranty from the date of shipment. In the event of a warranty claim, NINERMAS provides replacement or repair support with priority handling for production-critical applications.

Q4: Can NINERMAS support bulk orders or urgent supply requirements for ongoing maintenance contracts?
Yes. NINERMAS maintains stock of the 6ES7138-4FA02-0AB0 and related ET 200S components to support both spot purchases and scheduled maintenance contracts. For urgent requirements, same-day dispatch is available subject to stock confirmation. Contact our sales team directly to discuss volume pricing and lead time commitments.

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