Replacing a 140CPU43412 With a 140CPU43412A CPU

140CPU43412A CPU

Replacing a 140CPU43412 With a 140CPU43412A CPU

One of the more common Modicon Quantum CPU modules is the 140CPU43412A CPU module. This unit replaced the 140CPU43412 unit which has since become obsolete. Currently, many systems are being updated so we consistently get questions about 140CPU43412A CPU replacement and what the differences between the two units are, and if they are plug-and-play replacements. To help with this transition, we put together a few notes to help anyone who has questions.

The redesigned unit designated with the “A” at the end is functionally identical to the original non-“A” unit, with a few slight considerations. If you are using this CPU in a hot standby system, you must use matching units, so either two 140CPU43412 units or two 140CPU43412A units. Additionally, the 140CPU43412A version has a unique flash executive, and the two unit’s flash executives are not interchangeable. For the software, all the standard systems (Concept, ProWORX, and Modsoft) support the 140CPU43412A unit, and any 140CPU43412 program will load directly on to the new 140CPU43412A without needing to be changed.

MRO Electric stocks new and refurbished Modicon Quantum parts.  We also provide pre-priced Control Techniques repairs. For more information or to request a quote, please call 800-691-8511 or email

Updated on March 5, 2020 by Brian Hughes

Joe Kaminski

Joe Kaminski is an industrial automation specialist at MRO Electric. He has a background in industrial engineering and supply chain management. Joe has worked in the automation industry for over 10 years providing support to some of the largest companies in the world. For more info, visit

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