instrument calibration for true value calculator in rslogix5000

hello all

i have to made a calculator of 100 and more transmitter value coming from field that would be my uncorrected value and i have to find true value of the uncorrected value.
so is there any tool for the calibration of the this while i know the reservoir temperature.
ok let’s suppose this way. There is reservoir whose temperature is measured by(pt001)
Reservoir temp
Corresponding error
15
.5
17.5
.6
20
.7
22
.8
25
.9
more
more
Suppose our pt001 is 16 degree temperature then it lies between 17.5(max test point) and 15 (min testpoint) then corresponding error max and min through this way we got scaled true value.ok
But here matter is that pt001 temperature lie any of the temp we have to find corresponding max,min test points and error? Is there any tool in ladder or any math function such that if pt001 temperature comes and corresponding min ,max test points and error I got automatically..
Please help me on this …

md.abdullah,

The most common method is to average the temperature inputs over some time period. If you know the Maximum and Minimun, you can filter the inputs so that only temperatures within range are averaged. For example, if you take a reading every second for 5 seconds, then divide by 5, then the Temp Average = (T1 + T2 + T3 + T4 + T5) / 5.

Lancie what is he asking? I am missing what he us trying to do.

How are you determining that the 'true' resevoir temperature is 16.0° ?

From your reported data, an RTD indicated value of 16° would have an error of something between 0.5 and 0.6. Correct?



How have you determined the values that your report?

By the way, putting values into excel and taking a screen shot, or posting the excel file makes it easier to read values. If your data is hard to read, readers will skip over it.

JeffKiper said:

Lancie what is he asking? I am missing what he us trying to do.

Click to expand...

My Translation of the question into English:

Is there any tool in ladder, or any math function [such that I [will get] automatically the temperature value], [and takes into account the] corresponding temperature min, max, test points, and error?

Click to expand...

My best guess is that he has a process temperature input that varies, and he wants to find a reasonably stable approximation of that temperature (average value). He would like to use "automatic" (built-in predefined) functions to calculate this average temperature value, if possible.

I suspect that somehow or other the OP made measurements over a temperature range that show an error that varies from some standard (a thermometer?), because the error seems to increase slightly with an increase in temperature, but it's not a linear error.

If that's true, he's probably asking how to determine a correction factor (equation) that can correct the
indicated reading to a corrected value reading.

But it's a difficult assessment.

He has a history of participating in his threads, so he'll probably be back.

yes you are right
i need correction of indicated value
any tool?

There is a Function generator function block, named FGEN.

It is a multi-point look up table.



Check out the pages 36-38 in this document for an example:
http://www.t-bak.com/Process Control Configuration in ControlLogix.pdf

can you provide me some attached data upon it?
if i made fgen i got xy value then i have to move this value to the several particular add on instruction
so these value can be easily moved simply by pointer or..etc
suggest me

also look this one
http://www.plctalk.net/qanda/showthread.php?t=66322
any help

I don't have access to RSLogix in any version, so I can't give you details.

The data you need is the 'as-read' value and whatever you've determined is the 'true' value.

Generally these look-up tables have a column of 'as-read' values and for each 'as-read' value, a corresponding column in which to enter a corrected value that you want the 'as-read' value corrected to. The corrected value is typically not the error, it is the corrected value itself.

You have to make sure that you cover the range of the input. If you haven't made measurements at either end of the span, include 'as-read' values and the same value for the corrected value at whichever end (lower and/or upper end) of the span where you don't have corrected measurements.

This is not RS-Logix, it is another brand Process Automation controller. But the concept is the same, even though the FGEN is used to characterize the PID output, not the analog input: