Heat Bed setting off Strain Gauge

Lightpath

I have a new Duet Smart Effector I bought from Filastruder. I have set it up and it seems to be working well when the heat bed is off. When the heat bed is on, if I get within 100mm of it the strain detector goes off. I know it's the heat bed because I can take everything off of the effector except for the 8 pin connection back to the Duet, and with the heat bed on as soon as I move the empty effector within say 100mm of the heat bed the light comes on and the Z probe reads 1000 in the Duet interface. Here is my setup:

; Z-Probe for Duet Smart Effector
M558 P8 C"^zprobe.in" R0.4 F1200 T5000 H5
G31 P500 X0 Y0 Z-0.10 ; set Z probe trigger value, offset and trigger height
M557 R100 S20 ; define mesh grid

And for the heat bed:

M308 S0 P"bedtemp" Y"thermistor" T100000 B3950 ; configure sensor 0 as thermistor on pin bedtemp
M950 H0 C"bedheat" T0 ; create bed heater output on bedheat and map it to sensor 0
M307 H0 R0.300 C505.0 D1.98 S1.00 V17.6

The heat bed is a SeeMeCNC Onyx 300mm bed powered off the Duet at 24 volts.

I've tried manipulating the sensitivity, but when I send M672 S105:50:205 for example, the web interface says the command was successful, however the duet status light doesn't flash like I would expect it to. When the duet is powered on the status LED flashes twice, when I would expect it to flash three times if it was operating normally.

From reading other posts it appears I have no real choice here but to send it back to Filastruder? I bought it in the last month so I'm not concerned with warranty, I just don't leave my apartment much since Covid. Is there no way to use the unpopulated programming header to program it myself? I have pogo pins and headers, is there a way to program it if I can get everything connected, say with the regular Arduino IDE?

Open to any and all suggestions.

One more question- Can I go back to FSRs with the Smart Effector still in place? It's not a bad quick-change platform even without the z-probe.

Thanks very much!

Lightpath

For the next person fighting with reprogramming the sensitivity change your M558 command

FROM:
try C"zprobe.in"

TO:

C"zprobe.in+zprobe.mod"

And you'll be able to set the sensitivity. @dc42 Can I add this to the documentation or could a MOD please do it?

dc42

@Lightpath, use the B1 parameter in the M558 command to turn heaters off during probing.

The bed heater must be creating sufficient magnetic field to be picked up by the strain gauge amplifier.

Lightpath

Oh good lord look at the Gcode dictionary for M558. There it is right there:

"Bn If 1, turn off all heaters while probing, default (B0) leaves heaters on. (RepRapFirmware 1.21 and later)"

Thank you @dc42