Mitsubishi P460/P461 alarm: Program or format error

Mitsubishi control detects invalid format or command in the program. It is an alarm from the Program area, and in the catalog it is listed as “Program or format error”. On the machine you notice it like this: The program stops at a block, Fails after changing post-processor or control.

On the shop floor it almost always comes from one of these causes: G/M code not supported, Wrong address, Incompatible cycle parameter. Rule out the most likely one on your machine first, before touching parameters or swapping anything.

Reset after correcting the program and repositioning insurance. Resetting without fixing the cause first only hides the problem: Mitsubishi P460/P461 trips again and, in the meantime, you keep working with the machine in bad shape.

With the machine stopped and in a safe state, start with these checks: Write down exact line, Compare against the active G/M list, Review machine mode and active plane. That alone will tell you whether it is the program or whether you need to raise a maintenance job.

With Mitsubishi P460/P461 active, avoid this: Do not execute corrected block without simulation/single block, Do not mix Fanuc/Mitsubishi syntax without validating it. Skipping any of these points is what turns a minor stop into an expensive breakdown.

If previously valid programs begin to fail without changes. If you are not sure how far it goes, stop the machine and report it: a repeat alarm always works out cheaper than a crash.

It is a stop alarm: the cycle will not continue until you fix the cause. It does not always mean serious damage, but it leaves the machine where it is and you have to check it before running again. The code list changes by Mitsubishi series and installed options.