Micro Logix 1000 Analog input comparision

mikewood

Member
Join Date
Jun 2004
Location
Baltimore, MD
Posts
13
I am using a Micro logix 1000 with and analog input of 0 to 10
What I want to do is to compare the analog input with a present value.
and then make a desion base on this comparision. My question is, how do I store a preset value to use as the second part of the equation.
Example; the analog input represent a pressure of 0 to 1000 Torr. At some predetermine pressure, say 750 Torr I wish to energize a valve to start a vacuum cycle. The question is how do I store the 750 Torr value for camparision to the analog input.

Thanks,
Mike
 
MicroLogix

Mike I think can you use a compare statement, such as a (Limiter) show the low limit as to what (torr?) you want the unit too turn on and a high limit as too what you want the unit to turn off. Set the test part of the limiter as the analog input?
 
You should be able to directly compare the integer you assign the analog signal to to any other value using an EQU, NEQ, GEG, GRT, LEQ, or LES instruction. For Example if you assigned the analog to N10:10 and the vacuum is desired above 750, then use a GEQ that goes true when N10:10 is Greater than/EQual to 750.
 
Last edited:
That's ok if you don't expect to change the setpoints.
But why not scale the input value to engineering units and
then deal with some meaniningful values? It will save you
time next time you want to look into code, change presets
etc.
 
analog

Hi Mike
I believe you are going to have to scale your 0 to 10v. It`s going to come to your analog word as 0 to 32767. Go to Help then help with SLC 500 instructions click on SCL and it will show you how to do this. It looks harder than it is print it out and it will be simple ONCE you understand it. Then you can use the compare with what ever word you scale your signal into. In programming the SCL instruction shows up in FILES/MICS
Good Luck
Tom bonkhead
 

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