naj.keclv

FB rewrites edted value with value from previous cycle

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Hello dear PLC gurus :),

i seem to have a bit odd one problem, i created a function block to manage conveyors. In this function i can set (by input) memory bit MT_1 (Memory transfer 1) of In/out data. Which is used as value transfer (telling me something should be in motion). This memory bit can reset by another input. Problem is that when in one cycle after i set this memory bit. In another cycle MT_1 is reset. There is no way a reset that bit with my input to reset it. I am thinking that maybe function hold value from previous cycle and somehow rewrites already set value.

I made changes so the program is more "robust", and because i dont have reason to be input variables, which are used to set or reset MT_1 to be just pulses. i made them last for multiple cycles. But i worry about what this problem can cause in other seemingly alright working parts of my program. Nowhere else i write to this bit MT_1 or operate with data space which is assigned to this bit.

Did someone have a similar problem?

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