Reading an integer from a table.

[Myke Rocks 0]

I am working with an SLC 5/05

With Mitsubishi, I can use a "V" offset to read a value out of a data table.

I wish to do the same thing in Allen Bradley, and cannot figure out how to do to or what command to use.

Thus, I have an irregular shaped vessel. I have a pressure sensor reading weight of liquid in vessel.

I have the true values in an Integer table (250 Integers) and wish to read the true weight via a scaled signal from pressure transducer. (250 level points)

Would someone be so good as to suggest the command to do this?

Regards Michael

[panic mode 246]

whatever platform you are working with, you need to have your reference documents for that platform at your fingertips. and SLC500 is no different.

https://literature.rockwellautomation.com/idc/groups/literature/documents/rm/1747-rm001_-en-p.pdf

 

SLC supports indirect addressing so it is not a problem to access register using an index. it is same as using an array.

suppose you values are in table N27 and index value is in N7:34 and the result is in N7:35, you can use something like

SCP I4:0 3277 32767 0 250 N7:34; scale analog input with raw values range 3277-32767 to an engineering units 0-250 ton and place result into N7:34

MOV N27:[N7:34] N7:35; get value from lookup table N27 and put result into N7:35 based on scaled analog input value

but... using the integer data table as a lookup table to get result means you only have 250 values that can be displayed (no decimals).

and while that may be sufficient and meet your application requirements, it does sounds pretty low resolution compared to what one normally gets from the sensor.

[Myke Rocks 0]

Thank you for the prompt reply.

Analogue Input already scaled and waiting.

Will go to site and try rest of it it today.

Re; apparently poor resolution. Vessels hold a total of circa 54.5 cubic metres / 71 tonnes of product in an impossibly convoluted shapes. A conventional level sensor cannot be installed. The customer uses circa 15 tonnes per day, and this is just for monitoring and re-ordering purposes.

There is no control function whatsoever, and at a resolution of 250 provides weight to within +-10kg. +- 3 tonnes would be good enough for customer!

Result goes to HMI/SCADA only.

Will keep you posted on how I get on.

Regards Myke

[Myke Rocks 0]

Thanks again for the help.

Worked just as you said. I could not find information on this in intelligible form on Allen Bradley help functions.

Vessels fully Scaled, tested and operational. Absolutely brilliant.

Thanks again

Myke