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Edvin.M

Temperature control

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Dear all,

Have any one some simple project some simple temperature controller for SAMBA . I need it for control temperature from 0 to 200 C.  It is simple oven.  I have one thermoresistor  transmitter for Pt100 to use the input 4..20 mA on Samba SM35 - J- T20. 

I need some help or sample.

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Have a look at some of the examples listed under Analog Flow and Totalizing under Help/Examples/Version 900/Project examples.  There is a huge array of projects in the entire examples folio that give guidance for most questions.

cheers, Aus

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First you need to scale your analog input that you have your RTD connected to.  What are the specs on your RTD transmitter?

From the -T20 specifications:

image.png.02ba18e7d80c8f366a9d6f2dd510e374.png

You've mapped MI 0 to Analog Input 0.  So at 4 mA MI 0  will return 204, and at 20 mA it will read 1023, which is the output from the 10 bit A/D converter.  You need to know what real temperatures that corresponds to and us a LINEAR block to do the scaling before you feed it into the PID block.  Read the Help on how this block works.

A common spec for an RTD transmitter is 4/20 mA = 0 - 250 C.  Here's how the LINEAR block should look for this scaling:

image.png.8f1268a377d13f374d5780c0b467edd6.png

The PID CONFIG block should only be called once at startup, and the input should be the scaled temperature:

image.png.d648dd69efd3e2f383ebc50d43ac99de.png

You have to put values in the input parameters before the PID block will function.  You can use the power-up values to eliminate setting them with the program.

Now the big question - do you know how PID works?  The output of the block will be an analog value that will span between the Control Value high and low limits.  I put some in for you, but if you don't understand what they mean you need to spend some time reading ALL the Help on the block.  You'll probably have to convert the output to some kind of time proportional signal to drive a discrete output.  You'll also have to run Auto-Tune or set the P, I, and D parameters manually while it's running.

Joe T.

 

 

 

 

 

Termotunel JT.vlp

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Joe,

Please I need you help.  I have problem with PID !!! I don´get the PID: Control Value - the PID output I did´t see the fail.  I have setup the PID configuration . But I have some bug in program. Are you able to look at it maybe correct it. 

I have take form Unitroncs Test PLC for testing the possibility to work out the program for this machine.

I have this situation my Input signal is some PT 100  and with them i have to control some temperature in machine, but my controller i some proportional valve 0-10 V DC  

Second step is when I get this to control the steps of heating with time at sample 3 C in one minute.  But that´s is second step.

Please look at program Main Module  ; 0 GLAVNI MODUL ;  net 64;65 

 

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