ajsteinm

In my application, I am trying to control a Peltier, or thermoelectric device. Would you help me understand the logic in the program I inherited? The program has two PID loops, one that outputs heat, and another that outputs cool. When heating, cooling is inhibited. Any suggestions on better ways to do this? Maybe a single PID with two outputs? Just in case, a peltier device has two sides, a main and a waste. When current is flows though one way, the main side gets colder and the waste side heats. When the polarity is reversed, the main side heats and the waste side cools.

Thanks for the tips. I did not know about the ASCII keyboard.

I'm looking for tips on how I can allow an end user to change a text box from the PLC. My program has a system name on the top of the HMI as a text box, currently "SYSTEM 1". I would like the user to be able to change this to anything they would like. Ex: "TOP SYSTEM", "BOB". Currenlty, the only way I can think to do this would be create a numeric data table which assigns each letter a number, then let the user enter the numeric, and have the program convert the numeric to text. Ex: If A=01, B=02, C=03... Z=26, [space]=27 User inputs: 021221052713010308091405 Program Outputs: BLUE MACHINE