Auto-tuning the XMT7100 PID controller
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Has anyone had any experience with the XMT7100 PID controller? I have got it working after a fashion, but it is not behaving in the same way as the Watlow 935 that it replaced. The set point seems to be very much a notional concept to it; the temperature varies a lot around it. I set it to 218 degrees Fahrenheit, and watched it sail up to 223, at which point the pressurestat (which I had left inline and set it up high) kicked in. I have auto-tuned it 3 times so far, and it still doesn't seem to be very accurate. I left all of the PID parameters as factory set.
The information sheet is rather cryptic, and doesn't seem to mention a particular setting that I see; from power on if one changes the set point by pushing the up or down arrows, and then presses the Set key, the display shows 4 flashing 0000s, which suggests another setting, but the info sheet doesn't say what this is. Pressing Set again returns to normal operation. Does anyone know what this setting is?
The information sheet is rather cryptic, and doesn't seem to mention a particular setting that I see; from power on if one changes the set point by pushing the up or down arrows, and then presses the Set key, the display shows 4 flashing 0000s, which suggests another setting, but the info sheet doesn't say what this is. Pressing Set again returns to normal operation. Does anyone know what this setting is?
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Have you seen the manual? There are a couple version of XMT7100 around but the settings are generally the same. http://www.berriman.co.uk/wp-content/up ... mt7100.pdf
At the 0000 display screen, you can go to the PID values screen by changing 0000 to '0036' (using the >, up, and down buttons, and click 'set'). To enter the controller configuration screen, change it to '0089' instead. The details are in the manual linked above.
I too used the autotune function. While it's not perfect, it does a good job for my need. The most overshoot I've seen is ~1-1.5 deg C after steaming milk. It makes sense because I autotuned the controller with the boiler is at idle condition, so it is definitely not tuned for fluctuation/unsteady state.
At the 0000 display screen, you can go to the PID values screen by changing 0000 to '0036' (using the >, up, and down buttons, and click 'set'). To enter the controller configuration screen, change it to '0089' instead. The details are in the manual linked above.
I too used the autotune function. While it's not perfect, it does a good job for my need. The most overshoot I've seen is ~1-1.5 deg C after steaming milk. It makes sense because I autotuned the controller with the boiler is at idle condition, so it is definitely not tuned for fluctuation/unsteady state.