RSLogix 5 Analog Scaling

Hello there!

I am just a few minutes into this and here is my first post. Hopefully this works out! I am very new to Allen Bradley programming.

Anyway, I am trying to replace 4 proximity switches with a laser. The laser needs to be able to tell the RSLogix5 to execute at 4 different positions.

System Information:

RSLogix5
16 channel analog input card
Input card: 1771-IFE Series C
4-20 mA signal scaled to 0"-50"

I’ve done some digging and can’t seem to find a great way to scale an analog signal in RSLogix5. So far, all I’ve come up with is to make 4 different 'LIM' blocks to create a range that matches the existing proximity switches.

Any help is great help! Hopefully I provided enough information. If more is needed please let me know!
 
Raw data for this module should be 0-4095. I would just DIV the raw data integer by 81.9 to a float for 0-50 inches value. Four LIMs is a fine way to get the positions.
 
D

David Ferguson

You can scale the raw signals right in the logix 5 software.....

I'm not at my computer, and it's been a while, but you scale them in the analog card setups....

It is in the IFE manual. If you can't find it, I can when at a computer...just let me know. Did many many cards this way for ages. Haven't done PLC5 in a while though other than to convert them :).

Dave Ferguson
Control Systems Engineer
 
S
SLC has SCP, which would work nice, can't remember if the PLC-5 does or not.

I think the 1771-IFE will scale to engineering units internally. I know some 1771 AI modules did. You BTW to some registers for EU min & max. Now the output will still be integer, so you probably want to do implied decimal, like 0-500 or 0-5000 rather than 0-50.

Also check the filter rate in the module if you're moving fast.
 
D

David Ferguson

It does; this is what I was trying to get at saying you can do it right in Logix 5......

Dave Ferguson
Control Systems Engineer
 
S
My post wasn't in response to yours. With the moderation delay, both of us submitted our responses to the OP before either of ours were showing on the thread.
 
Hi besides doing your own scaling in the program. doses this mean that the only way to get a working decimal point reading when scaling using the analog input cards min max values is by adding the extra zeros like shown in your example and then multiply the value by .1 to a float
 
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