SCP Instruction?

This is my first time using this instruction in school we used engineering units to scale our analog signal. However, it is not available for me to use. Can anyone explain why? The rest of the analog IO is scaled in the program using an SCP instruction, so I just followed suit. I have included an attachment of a screen shot of the task, but I will do my best of explaining it for those that do not care to download it. I created a SCP tag. My input is off of slot 4 ch2 and is setup as a DINT the input min is at 0 and max is at 32767. The output tag is also setup as a dint and scaled min is 0 and max is 30000, but I am not getting any value for my output. Do I have to use a different data type for my tags or what else could I be doing wrong?
Thanks in advance,
Fred

For whatever reason, Rockwell decided not to include the SCP instruction in the standard instruction set. You can download it and import it as an AOI (add on instruction). It is such a commonly used and handy instruction, I almost always make use of it.

If your program already has that AOI, you should be able to add an instance of it. Just make sure that the tags you use for the instruction as well as the destination are of the correct data type.

In your screenshot, it looks like the logic is live (green power rails), but not being called (Whey_Silo_Gallons should be close to the scaled max, unless it is overwritten elsewhere). Make sure the routine is being called.

Welcome to the forum!

I think you have worded your question in a misleading manner, suggesting that the SCP instruction "is not available for me to use". If I understand you correctly, it's available for you to use and you have used it just fine - it's just not giving you an output.

I'd bet that you've fallen for one of the classic blunders:
1- Never get involved in a land war in Asia
2- Never go in against a Sicilian when death is on the line
3- Never forget to call your subroutine

Thanks guys, and sorry for the original post. I meant the engineering units were not available. You guys nailed it I did not have a JSR in there for they whey silo "DUH!" rookie mistake.
Thanks
Fred

no SCP instruction? ... Inconceivable!

There is a scale instruction in FBD if you a) pay money for FBD programming license AND B) want to use FBD for scaling analogs.

Only certain cards give you the "scale in the card properties" option. Personally I prefer unscaled units coming from the card and doing the scaling in the code like you have now done.

AustralIan said:

There is a scale instruction in FBD if you a) pay money for FBD programming license AND B) want to use FBD for scaling analogs.

Only certain cards give you the "scale in the card properties" option. Personally I prefer unscaled units coming from the card and doing the scaling in the code like you have now done.

Click to expand...

I use the FBD and make a whole routine usually named "Scaling Analog". I saw it a couple years ago in a reference I was given to create a new program, and I really like it now. I can change all kinds of parameters in the SCL instruction while on line, and it shows cool little values near the inputs and outputs on the instruction, so I can look at them while commissioning. To each his own, I guess. Have a great rest of your week, folks.

If you use the PlantPAX blocks and icons, they recommend you scale in the block. That way if it needs to change an engineer (not programmer) can change via the faceplate.