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vrf PID Control

Question asked by VRFuser on Oct 19, 2003
Latest reply on Oct 19, 2003 by VRFuser
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><HTML><HEAD><META http-equiv=Content-Type content="text/html; charset=iso-8859-1"><META content="MSHTML 6.00.2800.1264" name=GENERATOR><STYLE></STYLE></HEAD><BODY bgColor=#ffffff><DIV><FONT face=Arial size=2>Hi,</FONT></DIV><DIV><FONT face=Arial size=2>maybe it's not the answer to your question. I also had to handle this problem.</FONT></DIV><DIV><FONT face=Arial size=2>I used a ZILOG Z84 and later an 16F877 to control a probe temperature up to </FONT></DIV><DIV><FONT face=Arial size=2>300C ( about 5/min ) via a 150W heater switched by a zero-voltage triac. Because of the delay of this heater I didn't succeed using the PID algorithm (though it's sure possible).</FONT></DIV><DIV><FONT face=Arial size=2>I preferred the physical way, means temperature increases direct with the heater current and decreases proportional to the temperatur difference probe-environment.</FONT></DIV><DIV><FONT face=Arial size=2>With some measurments ( heating and cooling down under different constant conditions) I got a polynom descibing the system. (Only in case there was a simple proportional control overlaid, which was nearly never in action).</FONT></DIV><DIV><FONT face=Arial size=2>In the range 25-300C there was a deviation from setpoint |= 0.1 C.</FONT></DIV><DIV><FONT face=Arial size=2>Communication via RS232 too.</FONT></DIV><DIV><FONT face=Arial size=2></FONT> </DIV><DIV><FONT face=Arial size=2>Detlef Kersten  </FONT></DIV><DIV> </DIV>---<BR>You are currently subscribed to vrf as:<BR>To subscribe send a blank email to "".<BR>To unsubscribe send a blank email to "".<BR>To send messages to this mailing list,  email "".  <BR>If you need help with the mailing list send a message to "".</BODY></HTML>