AB: scaling an analog input signal in the 1769-IF8/A card

Hi all,

I'm studying how to configure my analog input module (1769-IF8/A)so that to scale my input signal from raw to a scale defined by me (I want it be from 0.0 to 10000.0, REAL type variable).

Under the tab "Configuration" in the attached screencapture I can see 4 available options:

Raw/Proportional
Engineering Units
Scaled for PID
Percent Range

Could someone here please give me some more extended information about what is intended to be each of these options?

I guess Engineering Units is referred to a scale 0 to 100 though I'm not sure at all. What in any case I want to is to set my scale to 0 to 10000 and it must be any "user defined" option I can't see around that allows me to do this.

Hope you can help me, thanks in advance.

buhnen, in the Analog Module User Manual in the LINK at page 3-28 you may find the valid input ranges based on your selection format.

To obtain a "user range" you need to scale the value coming from module.

If you have RS5000 v16 or v17, you may use an Add-On instruction that you may download from this LINK (Sample Code from Rockwell)

Here an example on how to configure your Add-On scale instruction.

Input - Input Channel address
Input Min - 0
Input Max - 32767 (check if this value is right for your input channel range/format)

Scaled Min - 0.0
Scaled Max - 10000.0 (example of floating engineering units)

Output - RealInputTag (your tag scaled and converted in real to use in PLC program)

Hope this helps....

- [font=comic sans ms,sans-serif]fuzzy logic[/font]

Unlike ControlLogix, CompactLogix analog input modules do not have the feature to scale each input in a custom range. Personallly, I'm using Engineering Units as it gives you direct mA reading (scaling is from 4000 to 20000), and then I'm using scaling instruction to rescale it into range I need. Ladder logic does not have such instruction and you have to go with function block SCL.
Good luck

Thank you both for your tips guys.

I'm quite a newbie to function block language. Usually with ladder and some variables kind of user-defined variables I manage to work with pointers. This means that with a small piece of code I can scale all my 11 analog inputs.

Instead of ladder, with function blocks my question is next: Should I draw 11 scaling blocks for each of the analog inputs I want to scale?

I've been reading more in depth the user manual of the IF-8 module and found a table where I can chose the required sets for my project.

In accordance with this table, for an input range 4-20 mA and chosing the "Percent Full Range" mode (discarding the other three modes) my analog input signal will be scaled to a range 0-10000.

So far , so good because this was my targeted scale.

BUT

though each of my input signals (11 signals) will be scaled to 0-10000 , I will need to use one or more of them for programming PIDE functions...and here comes my new doubt: when I check the aforesaid table I can see that there's a cathegory or function mode called "Scaled-for-PID" working in a range of 0-16383.

So...should I scale the required signals which I'll link to the PIDE in the range 0-16383 in contradistinction to the rest that will be scaled 0 to 10000?
or could I still use the PIDE within the scale 0-10000 adjusting any parametre in it?

one more question...are those 4 available scaling modes in INT,DINT (or REAL) data?