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HMI + Forced input states problem


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In my UniLogic project I have some binary text objects associated with digital input bits. I expect that the text inside the text object changes accordingly to the associated bit, in this case the state of the digital input pin then.

Going online to debug the program I am forcing the input state of the digital input pins and nothing happens, the text in binary text object does not change.
If I apply a voltage to the digital input, so that it reads 1, the binary text changes as expected.

If in a rung I insert a contact associated to the digital input bit that drives a coil associated to a memory bit variable, then if in HMI I associate the binary text object to that bit variable, I can see it changing if in online mode I force the state of the digital input.

Does anyone know a fix to this annoying bug? If the PLC is not nearby it's a pain to debug and I'd like to avoid to mirror all the digital inputs on bit variables just to fix this.


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  • MVP 2023

For what it's worth, I have a similar issue in Visilogic, and have put up with it for many years.  If I force an output online, the corresponding use of the output as in input throughout the program does not change state to correctly match what is actually happening. 

This can be a complete pita.  I have to put a manual overide contact before any error checking ladderwork, so that I can temporarily prevent a complete shutdown though me simply checking some action.

cheers, Aus

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23 hours ago, Ofir said:


We tested this and got the same results. We passed it to our R&D.

In the meantime you will need to use coil of another bit as you mentioned above.

Sorry for the inconvenience.


On 3/11/2019 at 5:25 AM, NoamM said:

Hi Fotonic,
Thanks for the input. I will pass it to our Support team. Next time please use the "Help center" at https://support.unitronics.com/index.php

Many thanks for interesting, I'll use the provided link for future requests.

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