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.