Control of Keenovo heat bed.
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Resistive loads like heaters can be challenging - leave them on too long and the thermal inertia will blow the 'setpoint' easily, leave them off too long and they won't reach it. The optimum would be to have more off than on but even that changes depending upon your setpoint. A heater that is too large can easily run rampant with even the smallest input.
I think the real answer depends upon your set up - try the lowest Hz number that gives stable control - can you even trend the temperatures in the Duet (more to read) ...
But we're digressing far from the OP's question - one hting that I will say is if you go more than 20% of the rated load then a heatsink is mandatory on the SSR or it won't live long. Thermal protection should also be on the mandatory list - SSR's tend to fail 'on'
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The default 10 hz works just fine for me on a 1200W heat bed.
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@jens55 said in Control of Keenovo heat bed.:
The default 10 hz
is it? i asked because i tried:
(maybe the experiment is flawed?) -
I am pretty sure it is 10hz for the Duet2wifi as I did not explicitly set up frequency. Are you running 2 or 3 ?
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@jens55 said in Control of Keenovo heat bed.:
Are you running 2 or 3 ?
RFF3 on Duet 3, just don't recall reading it changed, or mentioned in the upgrade notes and its potentially a bit of a big deal. Will fire up the Maestro and see if there is a difference between RRF2 and RFF3 when i get a chance.
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Bearer - do you have an M308 line defining the sensor before the M950 line ?
That said the gcode documentation for M950 states
T Temperature sensor number, required only when creating a heater [not yet implemented]. See M308.
The online generation tool adds the sensor to the M950 line - perhaps the Tx serves no purpose but then how do you assign a sensor to the heater ???
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RRF2 and RRF3 on Duet 2 assume that heater 0 is the bed heater until you tell it otherwise using M141. RRF3 on Duet 3 doesn't have a default bed heater. The best option when using RRF3 with a SSR is to specify the frequency explicitly in the M950 command that creates that heater.
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@Garfield said in Control of Keenovo heat bed.:
Bearer - do you have an M308 line defining the sensor before the M950 line ?
to be honest i don't have a heather nor a sensor, the board is on a cnc router
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@dc42 said in Control of Keenovo heat bed.:
The best option when using RRF3 with a SSR is to specify the frequency explicitly in the M950 command that creates that heater.
That could probably have been made clearer somewhere, but makes sense as you move away from predefined roles for pins. Thanks for clearing that up!
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@dc42 said in Control of Keenovo heat bed.:
M950 command that creates that heater
So is the gcode documentation in error - is the T statement implemented now ?
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Yes, it's been implemented for a long time.
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No worries - needs updating in the documentation.
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@droftarts, please fix this, also check whether the RRF3 wiki page has the same error. I'm on a smartphone, otherwise I'd do it myself.
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It's OK on reprap.org
On this page it says not yet implemented
https://duet3d.dozuki.com/Wiki/Gcode#Section_M950_Create_heater_fan_or_GPIO_servo_pin
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@dc42 Updated Gcode page, removed "not yet implemented". https://duet3d.dozuki.com/Wiki/Gcode?revisionid=HEAD#Section_M950_Create_heater_fan_or_GPIO_servo_pin
RRF3 wiki page was correct already. https://duet3d.dozuki.com/Wiki/RepRapFirmware_3_overview#Section_M950_Create_heater_fan_or_GPIO_servo_portIan