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Minor bug in Modbus master configuration


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There is a bug (i assume that is not 'by design' due to some unknown reason) in Modbus master config.

While it is said (in help), you can individually disable Periodic Registers, by putting their respective Active bits low, you cannot do it by putting General.OFF bit constant directly into config.

Instead you have to make bit variable, assign General.OFF to it, and then put that variable into config. That way it is finally accepted.

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General.OFF is a bit which is always set to 0, while General.ON is a bit which is always set to 1.

There is no point of defining a periodic Register with General.OFF in their Active bit, because it will always be inactive. It's like writing a function in any programming language, and then when you are done, you comment it out.

Why are you trying to assign General.OFF info a bit you've created?

The bit has a value of either 0 or 1, if you didn't put any value into that bit with powerup-value, by ladder or by HMI, then it will be 0. 

If that bit is not retained, and the CPU or the PLC are restarted, then the bit will be 0.

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