What to check before replacing an obsolete PLC module
Use the order code, OEM successor record, and installed configuration together.
Confirm the original order number
Record the complete Siemens order number, installed terminal or BaseUnit, controller model, and hardware or firmware revision. Preserve the engineering project and relevant maintenance drawings.
The 6ES7134-6HD00-0BA1 catalog identifies a 4-channel voltage/current input module and specifies BaseUnit types A0 and A1. Compare the actual signal wiring and configuration, not just the module width.
Check the successor’s current lifecycle
A successor is an OEM relationship, not an availability promise. Read the successor’s own record. Older ET 200S successor modules can themselves be in the spare-part phase.
The linked 6ES7135-4FB00-0AB0 research page separates the original and successor. It also leaves installation compatibility unconfirmed.
Verify configuration before installation
Compare channel count, signal ranges, supply and load ratings, terminal assignment, diagnostics, and controller support. Confirm the engineering software and firmware requirements in the applicable manual.
Siemens ET 200SP product information identifies firmware conditions for R1 redundancy. A part-number relationship alone cannot establish behavior in that configuration. Use the manual revision for your installed system.