safety heater temperature control
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Hello. Im mounting a heater for my chamber. Apart from reading the chamber temperature, I also want to monitor the temperaute of the heaters to be sure they dont burn out. Im reading the docs but it is not clear to my how to use M143 to configure this extra control. My setup is a thermistor to read the chamber temeprature, and a thermocouple to measure the heater chamber resistor ( I have bought the temp DB for connecting the thermocouples to the duet3 board, it is a max3185 chip based board). Lets say I want the max temp of the heaters (not the chamber) to be 400 degrees, how should I set up the config in order to cut the power on the relay to shut down the heater when 400 degrees are reached?
The definition of the sensor is like this in my config:
M308 S3 P"spi.cs1"Y"thermocouple-max31855" K"J" A"chamber_resistors"
M143 H0 T3And so far I get an error: "Temperature reading error on sensor 3"
Thanks in advance
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@tinchus said in safety heater temperature control:
Hello. Im mounting a heater for my chamber. Apart from reading the chamber temperature, I also want to monitor the temperaute of the heaters to be sure they dont burn out. Im reading the docs but it is not clear to my how to use M143 to configure this extra control. My setup is a thermistor to read the chamber temeprature, and a thermocouple to measure the heater chamber resistor. Lets say I want the max temp of the heaters (not the chamber) to be 400 degrees, how should I set up the config in order to cut the power on the relay to shut down the heater when 400 degrees are reached?
Thanks in advance
Hmm, that's tricky. If I read you correctly you want to
control,monitor ,use one heating element with two sensors. One sensor is used to control the heater, the second sensor is merely used for an over temperature alarm condition of the element itself yes?If that is the case, I don't think you can do it because you'd need to define two sensors in the M950 for that heater. The wiki https://duet3d.dozuki.com/Wiki/Gcode#Section_M950_Create_heater_fan_spindle_or_GPIO_servo_pin states (quote):
M950 is used to create heaters, fans and GPIO ports and to assign pins to them. Each M950 command assigns a pin or pins to a single device. So every M950 command must have exactly one of the H, F, J, P or S parameters.
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@deckingman Thank you. I have update my original post with my actual config. But my problem is actually that: the documentation is not really clear for me. Im doing something wromg of course and I cant find what or how I should do it exactly.
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@tinchus I've looked again at the wiki and things have changed in RRF 3. It seems that you can indeed have up to 3 monitors for a heater. But you seem to be missing a few parameters in your M143, not least of which is the temperature value (the S parameter). https://duet3d.dozuki.com/Wiki/Gcode#Section_M143_in_RRF_3_01RC2_and_later
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@deckingman I got it, thanks for the tips, configuration done!
