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Technicus

LT_E Compare not working reliably

3 posts in this topic

Posted (edited)

Dear,

I discovered a problem in an existing program.

The output / marker should only go high when the actual pressure is lower than the set pressure. (Druk_laag)
However, we see the marker sporadically goes high / low (usually between 800.0  and 1000.0 ) But not turn '1' under the set value of < 50.0.
Marker is not written anywhere else, I used other markers to rule this out. but not different ...
I also tried this in the simulation and another PLC but the same problem.

According to the manual this should work like this

Is there something I misjudged?

 

vergelijker probleem.png

Edited by Technicus

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Hi Technicus,

at the first look the code looks good to me.

I´m using the LT_E function quite often and never had a problem exuting it.

 

I would chase if your are wiring M_Druk_laag_veilig is double assigned or you are writing a word to it somewhere else in the program.

Another option to try could be to use "LT" and AND the outpur with M8000.

You can also check the compiler result, if, for whatever reason, the compiler gives you any stupid output.

Try to observe your ENO output, if the function works properly.

 

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17 minutes ago, MarkusR said:

Hi Technicus,

at the first look the code looks good to me.

I´m using the LT_E function quite often and never had a problem exuting it.

 

I would chase if your are wiring M_Druk_laag_veilig is double assigned or you are writing a word to it somewhere else in the program.

Another option to try could be to use "LT" and AND the outpur with M8000.

You can also check the compiler result, if, for whatever reason, the compiler gives you any stupid output.

Try to observe your ENO output, if the function works properly.

Hi Markus,

Thanks i will try the and function and also check if  M_Druk_laag_veilig in the crossreference.
The output compiler result doesn't give a error on this tags.

 

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