Analog Scaling Problem...

Dear All

I am working on the same thing where I have GE fanuc 341 CPU series 90-30. I need to add three analog signal coming as 4-20 mA signal from the flow transmitter and need to display on citect SCADA.

the final value to be displayed on scada have the range 0 to 600 Cu m/hr. So please tell me how should I do my scaling in the PLC.

OR
Also please note that Citect SCADA is also having an option for scaling so can I put there as follow;

Raw zero scale :0 Raw Full: 32000

Engineering zero scale : 0 Eng Full: 600

please advice????

thanks and regards

No reply....!
Very nice thanks to all

rahilansari said:

No reply....!
Very nice thanks to all

Click to expand...

dont forget yesterday was the end of the world.....

Remember
not everyone programs FANUC
I dont and cant help you.
it is also the funny season - there is a good chance that the people who do know are away for a few days.
BE PATIENT

600=32000
6=320
3=160
1=160/3
simple maths for scale

We typically do all scaling in the HMI, pulling the raw values from the PLC. That way, if the analog transmitter is changed to one having a different range (it happens) you do not have to alter the PLC code, which often involves halting to download (which may be difficult to accomplish for some procces).

Hello,

Scaling:

output = ((input value - input low) / (input high - input low)) * (output high - output low) + output low

mbartoli said:

We typically do all scaling in the HMI, pulling the raw values from the PLC. That way, if the analog transmitter is changed to one having a different range (it happens) you do not have to alter the PLC code, which often involves halting to download (which may be difficult to accomplish for some procces).

Click to expand...

i don't really see advantage in this unless you can go with relative values in the process. with absolute value you must know what 32000 stands for, so for total interchangeability you would allow user to enter upper/lower limits, and use that in scaling

I have to say
- NO REPLY FROM THE OP
could not have been so important

Thanks to all of you for a wonderfull support..I did it and lets see if its work and if its not I will come back to you....Please see below what I did ...Is it OKK

|--------| |--------|-----------(+)
%AI--| ADD |--%R1 %R1--| MUL |--%R2
0--| INT | 600--| DINT |
|--------| |--------|

|+|--- |--------| |--------|
%R2--| DIV |--%R3 %R3--| SUB |--%R4
32000--| DINT | 0--| INT |
|--------| |--------|

/////|--------|////////// |--------|-----------(+)
%ai--|//add// |--%r1/%r1--|//mul// |--%r2
//0--|//int// |//////600--|//dint//|
/////|--------|////////// |--------|

|+|--- |--------|////////// |--------|
//%r2--|//div// |--%r3/%r3--|//sub///|--%r4
32000--|//dint//|////////0--|//int// |
///////|--------|////////// |--------|

If the span is truly 0 - 32000 (not 0 - 32767)
and the span maxes out at 20.00mA (not 21.5mA or 22.3mA or whatever)

then, 20.00 mA = 32000 counts
4.00 mA = 6400 counts

16 mA span = 25600 counts
each mA = 1600 counts

You have to be careful to avoid overlapping addresses in GE. When you specify DINT as the data type, the PLC uses two consecutive %R addresses. Your code will create all sorts of problems. Use DINT for everything.

First, MOVE_INT %AI to %R1 and move CONST 0 to %R2. Then use DINT for all your math instructions and use %R3, %R5, %R7 etc for the addresses. That will work OK as long as your %AI value never goes negative.

Do not use the %AI address in a DINT instruction because it will treat %AI1 and %AI2 as if they are a 32-bit integer when they are really two separate channels.

And by the way, to post your ladder logic, enclose the ladder between the html tags (ladder) and (/ladder) using square brackets instead of parentheses. That forces the board to use a fixed width font which correctly renders the spaces. Also, don't use the board topreview your code. The preview function strips extra consecutive spaces.

Thanks guys..
will follow all your suggesstions...and come back

rahilansari said:

|--------| |--------|-----------(+)
%AI--| ADD |--%R1 %R1--| MUL |--%R2
0--| INT | 600--| DINT |
|--------| |--------|

|+|--- |--------| |--------|
%R2--| DIV |--%R3 %R3--| SUB |--%R4
32000--| DINT | 0--| INT |
|--------| |--------|

Click to expand...

To draw ladder in a post on the forum, use the formatting options "ladder":

[ladder']

before you start "drawing", and after the pictographic, place this:

[/ladder']

Omit the quotations marks, I had to do that to get them to be visible and not acted on.

This turns off some of the formatting features. On the Advanced editor there is an icon for it i think.