If you want to display temperature on HMI then thebest way to do is to use one decimal point and no of digit can be decided my min and max range.


If your temp range is 0.0 to 150 deg C then format you can use is 999.9

Normally if you have RTD as analog input for temperature then you may need to divide the PIW256 by 10.0 to get exact temperature. But you have to convert the PIW integer to DI and then DI to Real, then divide the Real value by 10.0 you will get the result as real value.

Or you can use FC105 SCALE fuction from Siemens Standard library to scale & convert Integer to Real value. Here you need to put min and max temperature range to get correct result. Min is min temperature the sensor can sense and max is the max temp the sensor can sense.


Hope this answer will give you some idea.

teaboy

I have a problem where i have a Temperature signal PIW 256 and i need to convert it to a real number to display on an HMI

I can read the word value as 3 figures but i need to convert it to real so i can reduce the 3 figure value to a 2 figure value on the HMI i.e 25.4oC to 25oC


please can anybody offer assistance.

rit03

You can use IEC function block FC105 ( Scale Convert) presentin library to convert PIW value to real.