SCALING PLC sLC 500 RSVIEW32 Works

Objective: To replace a device ( chlorine analyzer ) which is 4-20ma with a device that (also a chlorine analyzer) 4-20ma. The first device is only capable of 0-5 ppm display and the second device is capable of 0-60 ppm. The objective is to make the display read 0-60 on the new device using RSview32 Allen Bradley and this is SLC500 logic. I am still learning as most of us do everyday and appreciate any help we can get. Thanks so much for reading and perhaps responding.

Search your logic of the PLC for the command SCP. ( scale with parameters) I am sure it will be used in your program. Then read the instructions help file. It will be quite easy to alter. Regards Alan Case

Search your logic of the PLC for the command SCP. ( scale with parameters) I am sure it will be used in your program.

Click to expand...

Don't be so sure.

It may be used but then again the SCL or math calculations might be used as well, IF the scaling is done in the PLC.

What you have to do is find the point in the RSView database. See if scaling is defined for the point. If not then the scaling is done in the PLC. If it is then the scaling has to be changed in RSView. That's relatively straight forward but post again if this is the case.

If the scaling is done in the PLC you should search for the address of the point in RSView. If you're lucky you'll find the SCP instruction mentioned above. If you're a little less lucky you'll find the SCL instruction mentioned above. If you're even less lucky you'll find a bunch of math instructions. If you're totally un-lucky you won't find a thing.

Regardless, if you don't find one of the scaling instructions or if you've got problems understanding the scaling instructions (if this is the case) then let us know and I'm sure someone here can get you going.

Good Luck,

(8{)} ( .)

(Yosi)

Out of curiousity is it possible to use a scratch register, ie an n or f register as an indirect address for a scale with parameter scale factor, have used SCP many times but never tried that one, actually never had an application to do that, but would be interested to know if it is possible.

I've done that. You can use indirect addressing all over the place with the SLC and PLC controllers.

You can't use a floating point value as a pointer (for obvious reasons) but all of the other parameters can be floats.

(8{)} ( .)

(Yosi)

Thanks (8{)} ( .)
Will remember that one, would come in handy I think in certain apps when calibration out a little an just need a slight tweek without draggin out the laptop.

Again, Thanks
Bill