X axis sensor - G31 returns zero

Hi,

I've been assembling my new Ormerod and so far everything has gone well. No mechanical problems, communications work well, firmware updated to "FIRMWARE_NAME:RepRapFirmware FIRMWARE_VERSION:0.39 ELECTRONICS: Duet DATE:2013-12-14", nozzle and bed heaters working...

I have now started checking the homing functions and I have a problem with the X axis.(Y works ok). I have read through the other posts, added reflective tape, turned off the lights etc but still nothing. I have checked with the G31 command and I always get a return value of 0.
>>>G31
SENDING:G31
0

This seems very strange. The X axis does not respond at all to a home command, and the Z axis drops a few mm then stops. Exactly what you'd expect to see if the Duet couldn't read anything from the sensor. However, I have measured the voltage on the blue wire and this is 0V with no target and rises to about 3V when an object is directly under the sensor. I can therefore assume that the sensor is plugged in the right way around and is working correctly but I still cannot get any value back from the G31 command other than 0. This blue wire is connected to the Duet board as per the photos (9th pin from the right on the bottom row of the expansion connector). The machine is powered from the ATX power supply and the 5V mod has been done.

Anyone got any ideas about what I've got wrong here?

Thanks in advance,
Ed.

Is the Z sensor turned on? This is normally done by the M558 P1 command in config.g.

Excellent, that fixed it thank you very much! I had to send M558 P1 manually from the Pronterface command even though M503 reports that this is turned on in the config file:

SENDING:M503
; RepRapPro Ormerod
; Standard configuration G Codes
M111 S1; Debug on
M550 POrmerod; Set the machine's name
M551 Preprap; Set the password
M552 P192.168.1.14; Set the IP address
M553 P255.255.255.0; Set netmask
M554 P192.168.1.1; Set the gateway
M555 P2; Emulate Marlin USB output
M92 E420; Set extruder steps/mm
G21 ; Work in mm
G90 ; Absolute positioning
M83 ; Extrusions relative
M558 P1 ; Turn Z Probe on
G31 Z0.5 P500 ; Set Z probe height and threshold
M906 X800 Y800 Z800 E800 ; Motor currents (mA)
T0 ; Select extruder 0

My guess is that this isn't being run at startup? This is no big problem for now - at least I can carry on with commissioning now that I can home X and Z.
Thank you once again!
Ed.

Sounds like your config.g file may not be running at startup. I had the same problem. If I pressed the Reset button on the Duet, config.g did get run. I fixed the problem by ditching the SD card that came with the kit and substituting a Maplin 4Gb Class 10 SD card. However, without config.g running, Pronterface didn't regard the printer as online and so couldn't connect (the precompiled Windows version of Pronterface I downloaded needs the "ok" responses, which require Marlin emulation to be turned on).

Edited 1 time(s). Last edit at 12/22/2013 10:42AM by dc42.

I had to manually run the M555 P2 command to turn on Marlin emulation and get Pronterface to recognize that the printer was online so it sounds like I have exactly the same problem. I think a new SD card is in order unless I can wrestle one from my RPi collection...

Thanks again - I'm absolutely certain that it would've taken me a very long time to get this far without your help and this forum!

Ed.

I thnk that makes three of us - trevor51 has just reported what sounds like the same problem.

Ian, I think you need to either supply faster SD cards, or change the firmware to allow the SD card more startup time.

Quote
dc42
Ian, I think you need to either supply faster SD cards, or change the firmware to allow the SD card more startup time.

I've already passed that suggestion on to the firmware team! I'm fed up of apologising for the stupid things...

Ian
RepRapPro tech support