simmo1973

logix 5000 hold function

5 posts in this topic

Hi,

does anyone know of a function in rslogix 5000 or plc5 that I can use to hold a maximum analogue input value until reset,

eg, pressure rising during a machine cycle upto 100+bar then drops of to 0 bar , I need to somehow hold the maximum value it reached in cycle until I reset.

thanks

 

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Hi simmo1973.

Firstly welcome to the forum.

Of course you can, in ladder logic this is quite simple.

So on first scan or the bit you use to request monitoring, one shot the current pressure to a holding register, then in parallel if the current value is less than the new value, move the new value into the holding register.

Once the conditions for your reset are fuffiled then move a 0 into the holding register.

If you doing this on many machines or routines, it may be worth making this into an AOI.

Does that make sense or?

 

Regards

Daniel

Edited by collinsd70

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Here is a screenshot of the logic and also the encapsulated AOI (Source unprotected).

Note the Tag "oHighest_Pressure" is only updated when the Start signal is high, on the falling edge of Start; the Highest Pressure tag will default back to 0.

 

Regards

Daniel

High_Capture.jpg

AOI_Capture_High.L5X

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Glad I could help Simmo, feel free to modify to suit your application.

 

Regards

Daniel

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