adding two 4 to 20 mA analog input to one output in slc 500 05

bks

Member
Join Date
Aug 2003
Posts
4
I have project using slc 500 and have to add two 4 to 20 Am signal in to one 4 to 20 Am analog out so that i can get total generator Kw I obviously have a mixed analog card with inputs and outputs and two 4 to 20 millamp inputs are provided by barber colman power R con units some help with ideas for the ladder to acheive this would be of great help
many thanks

:)
 
4..20mA

Hi!

You should consider that 4..20mA represent a real value. For example:
Input1:
4mA 0kW
20mA 100kW
Input2:
4mA 0kW
20mA 200kW
Output:
4mA 0kW
20mA 300kW

So what You could do is to convert 4..20mA inputs to its real value and then add then. After that you can convert to the 4..20mA in the output.

I hope this helps you.
Forgoselo

P.D. I can't help with SLC500 because I haven't work with it.
 
This task is relatively simple.....In the SLC 500 you will need to utilize the SCP instruction to bring the analog signal into the PLC and scale it to the engineering units required.

You will then need to write some logic for your totalizer. There are many different ways to write a totalizer, depending on the accuracy required. Do a search on this site for "totalizer" and you will see many posts, with example code.

Greg
 

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