Pt100 Converting block, s7300

[Egil-s]

Hi.

I have a Cpu 315-2 and I use a 13-bit analog module (6ES7 331-1KF01-0AB0) to measure a PT100 -50-200C.

I also have a MP 377 15" screen.

My question is; is there a converting block or something that i can use with the Pt100 sensor.

I use this to control a cooling fan on a hydraulic system.

I want to display the temperature on the MP377, real value in degrees Celsius.

(Pretty newb on this PLS thingy )

 

[userxyz]

hmm

FC105 = scaling function.

U can use PID

Hi.

I have a Cpu 315-2 and I use a 13-bit analog module (6ES7 331-1KF01-0AB0) to measure a PT100 -50-200C.

I also have a MP 377 15" screen.

My question is; is there a converting block or something that i can use with the Pt100 sensor.

I use this to control a cooling fan on a hydraulic system.

I want to display the temperature on the MP377, real value in degrees Celsius.

(Pretty newb on this PLS thingy )

 

[Egil-s]

Yeah, I though of that one too.

But when I try that block, i cant put any value in Hi/low limit.
Can't i just put in the high and low limit as Real? Low limit -50, High limit 200?

 

[userxyz]

hmm

FC105 should work, have no S7 open at the moment. Check google to find FC105 info, or PLCS.




Another method is: y = ax + b

x = INPUT / 27648
a = range
b = offset

Celciusvalue = 250 * x + (-50)

Example: 22000 integervalue input gives =>
(250 * (22000 / 27648)) - 50 = 148,92 degrees celcius


In code:

L PIW256
ITD
DTR
L 27648.0
/R
L 250.0
*R
L 50.0
-R
T MD50 // Value in Celcius

Yeah, I though of that one too.

But when I try that block, i cant put any value in Hi/low limit.
Can't i just put in the high and low limit as Real? Low limit -50, High limit 200?

 

[FARIAM]

Are you connecting the PT100 directly to the module?

If that is the case, you don't need a converting block at all. It will (depending on your hardware config) give you the value already in F or C degrees, multiplied by 10 or 100 (depends again on the resolution and Pt100 range).

If not (you are using a current or voltage signal), you can use the function FC105, where the High and Low limits are Real values, and so is the function output.

 

[Egil-s]

Ok, that can make sense. I have connected it directly yes.
Got a decimal value of 1002 when i used a hexadecimal converter online.

What is the easiest way to get a real value on the MP377?

 

[bara_hence]

Is the analog module set to measuere PT100 and not mA??

If its set to PT100 then the value you get in is an integer that directly represents temperature * 1000 example if you have 25.35degrees the value in is 2535...

If its a transmitter between with a mA signal then just use FC105 and you must use . as a decimal for example max = 200.0 low = 25.0

Hope I make any sense...

EDIT:

Oh and if its a PT100 input and you want it to real just move the int to a dint and use the round function and then divide the real with 100 and voila

 

[FARIAM]

Ok, that can make sense. I have connected it directly yes.
Got a decimal value of 1002 when i used a hexadecimal converter online.

What is the easiest way to get a real value on the MP377?

If the value is 1002 then the PT100 should be around 10,02 C right?. If that's true all you need to do is this (faster on AWL/STL):

L Value (PIW XXX)
ITD
DTR
L 100.0
/R
T Result (real tag)

If you need the tag "Result" on the MP377 just create a tag on WinCC Flexible with the Result address and Real data type.

If you have the WinCC Flexible project integrated with Step7 Project then you only need to select the Result symbol.

 

[joshua akassa]

I tried the above code and works fine, but why do i have to multiply the result by 10 to get the temperature value in degrees C.

L Value (PIW XXX)
ITD
DTR
L 100.0
/R
L10.0
*R
T Result (real tag)

 

[KalleOlsen]

I tried the above code and works fine, but why do i have to multiply the result by 10 to get the temperature value in degrees C.

L Value (PIW XXX)
ITD
DTR
L 100.0
/R
L10.0
*R
T Result (real tag)

Because the analog input is scaled in deci-degrees, look at the PIW in decimal format.

You can simplify the code a bit:
L Value (PIW XXX)
ITD
DTR
L 0.1
*R
T Result (real tag)

Kalle

 

[paeh]

hi..i just want to ask about the program. Could you teach me the program on LAD diagram..i am not familiar with STL