Precision Piezo Orion triggers when bed heater is active

runamoK

I have a Precision Piezo Orion connected to my Duet 2 Wifi.
The Orion is conected via the analog output.

If the bed heating is off, everything is fine and works as desired.
As soon as I switch on the heating bed the orion triggers. The blue light on the Orion is permanently active.
And the Z-Probe value, shown in the Duet Web Control status filed, jumps arround 600. When the bed heater is off this Value is stable at 540.

The heated bed is connected via a mosfet.

I just updated the firmware of the Duet to 2.05. The problem is the same.

Does anyone have a hint for me on why this problem occurs via the Orion's analog output?

I think it would work with the digital output of the orion. But I would like to adjust the sensitivity via the config.

@runamoK said in Precision Piezo Orion triggers when bed heater is active:

Precision Piezo Orion

I have not seen the schematic of the orion pcb (I have old version pre oreon and new andromeda's on old pcb too, no analog output on those) but it's possible the amp is picking up the noise... but is weird since orion is supposed to be on the extruder, bed heating is not that close to produce issue ..

have you tried the digital output? the "non stop blue" just means the "idle value" when the heater is on is above the set value, have you tried to configure the pot so that blue just dies out as you should when using digital output? and then read the values on the analog side? maybe if you have a scope read the analog output on the pcb itself and on the duet

gtj0

Uhm, I didn't think the Orion had an analog output. No mention of it in the docs. How did you get it to provide an analog signal?

Anyway, it sounds like electrical interference. Do the bed and probe cables run next to each other at any point?

runamoK

@smece said in Precision Piezo Orion triggers when bed heater is active:

have you tried the digital output?

I am currently testing the digital output. That seems to be working so far.

@gtj0 said in Precision Piezo Orion triggers when bed heater is active:

Uhm, I didn't think the Orion had an analog output. No mention of it in the docs. How did you get it to provide an analog signal?
Anyway, it sounds like electrical interference. Do the bed and probe cables run next to each other at any point?

The new Orion v2 has an analog output.
The note with the cables was a good idea, unfortunately nothing changes when I put them around the outside of the printer.

gtj0

Are you using PWM with the bed heater? If so, try turning it off or changing the PWM frequency and see if that makes a difference. When you say "The heated bed is connected via a mosfet", do you mean the Duet2 internal mosfet for the bed connector or an external one?

gtj0

One other thing to check... with the bed on, does the reading increase above 600 when you tap the nozzle or is it jut stuck there?

CaiJonas

Had an similiar problem. The solution was to ground the aluminium plate where I glued on the silion heat patch on. You could try this first

gtj0

@runamoK I just got my V2 in and am seeing a similar problem. For me, it's when the motors come on.

With M558 I0, before the motors come on, I read 530. As soon as they come on, I read 545. I have an idea that when the motors come on (or your bed) the 5v supply drops slightly and that changes the analog reference. Check with a multimeter or oscilloscope and see if +5v is changing.

Rakotouf

Hi, I know this problem is quite old, but I finally found out how to solve this, and did not know where else to share it. The piezo signal is very sensitive to electromagnetic interferences. The solution is to shorten this wire as much as possible and as far as possible from the power wires (heater, stepper motors...). A shielded wire may help maybe. So as a conclusion, place the PCB amplifier as close as possible to the piezos and protect the link between the piezos and the amplifier from electromagnetic fields as much as possible.