IMPORTANT ISSUE with bed temp controller

Luke'sLaboratory

@jrockland If the previous configuration was bang-bang, and instead we're using PWM @500hz, that could be a huge indicator of an issue.

jrockland

@Luke-sLaboratory Ill have to read more about bang bang but if I check on my other machines it is deactivated everywhere

dc42

Using an inverted heater output isn't safe. When you power up, you are relying on the Duet booting up and running that M950 command to turn the heater off. If any of that fails (for example, something prevents the Pi from running, e.g. the SD card goes bad), then the heater will remain on.

What connection are you using that requires an inverted heater output?

Luke'sLaboratory

@jrockland info on the relays would still be useful, but yes, probably should look into disabling PWM control if it was previously operated bang-bang and it was successful.

jrockland

@dc42 well that is the thing, it is inverted so it doesn't turn on as soon as I turn the board on. that is really weird. Ill have the board sent to my tech so he can look at it.

if I remove the inversion the board feed power as soon as it turn on (checked with a meter)

Veti

@jrockland said in IMPORTANT ISSUE with bed temp controller:

well that is the thing, it is inverted so it doesn't turn on as soon as I turn the board on.

this suggests you got the wrong ssr.

jrockland

@Veti ssr's are out of the equation, they are disconnected. Im testing the board whit a multimeter

dc42

@jrockland said in IMPORTANT ISSUE with bed temp controller:

@dc42 well that is the thing, it is inverted so it doesn't turn on as soon as I turn the board on. that is really weird. Ill have the board sent to my tech so he can look at it.

if I remove the inversion the board feed power as soon as it turn on (checked with a meter)

We really need to know what sort of relay or SSR you are using, and how you have connected it to the Duet. If it's a relay board then it may be better to connect it to an IO_x_OUT pin instead; but a SSR is better because it allows you to use PWM and hence PID.

Luke'sLaboratory

@dc42 He's talking about the actual board output, but I don't remember if i'm able to measure V_in across inactive outputs or not, since the ground is switched

jrockland

@dc42 on that specific machine we still use the old SRD-05VDC-SL-C, apparently we haven't blown them up yet. so no SSR'S on that one.

problem is probably in my gcode.

Luke'sLaboratory

@jrockland said in IMPORTANT ISSUE with bed temp controller:

SRD-05VDC-SL-C

Oh - so its a mechanical switch you were trying to drive with PWM. Well, that about "solves" it, other than inverting the heater signal. Datasheet shows ratings for 300 electrical switches/min, with only 30 mechanical switches/min allowed.

FWIW - this is why we always ask for the config.g when diagnosing issues.

Veti

as i said not having a quality ssr gives you a good chance of burning down your house

get some quality components like
Omron G3NA-210B-DC5 (10A) or Crydom D2425 (25A) or Crydom 84134000 (10A) SSR

jrockland

@Luke-sLaboratory driving relays with io's isn't the right way ? pretty sure it is what there telling us to do in the wiring diagram.. I might be wrong..

Veti

@jrockland said in IMPORTANT ISSUE with bed temp controller:

pretty sure it is what there telling us to do in the wiring diagram.. I might be wrong..

what wiring diagram?

Luke'sLaboratory

@jrockland IOs are fine, but you're trying to use a PWM signal (based on PID values) instead of a simple off/on. the mechanical relay can't keep up, and it may cause some other issues like latching on and causing the issue described. You'll need to re-enable Bang-bang, which will output either full voltage or none.

jrockland

@Veti O don't worry for me, theses machines are intended to crash so they have fire extinguishing system in place. and I don't run them in my house.

ever seen an axis with over 60lbs of torque crash ? parts goes flying XD

jrockland

@Luke-sLaboratory That would explain why it was working before the update, bang bang was probably activated before...

I will try to find how to write it properly using bang bang.

fcwilt

This post is deleted!

jrockland

@Luke-sLaboratory hmm wait if I look at my config file bang bang IS activated..

jrockland

@fcwilt you where right (before deleting your comment) but my config was set as using bang bang..