Help for Newby

[David Glass]

Just setting up my first board and job on a LitePlacer I have 2x fiducials on the baord but when the machine checks them it brings the nozzle down and rubs it on the boads during the homing. I have set -41mm for the board z when I take this out to 0 the nozzle behaves itself during fiducial homing but the components are then dropped 41mm from above the board.  It is probably something fundamental I am doing wrong could anyone guide me on setting up the z's for the boards, Parts, Packages and feeders to get the pick and place z positions right with the nozzle retracted during fiducial homing?

[tony...@att.net]

Set your logging level to trace, repeat the fiducial checks and post the resulting log file.  Also post your machine.xml file.

[David Glass]

Hi Tony thank you for your interest. I have attached all the files I think you could need. I just cant fathom where I need to set up the various z values for picking placing and fiducials. I am using standard Liteplacer hardware but opted for not trying to do z-probing - one less complication for the time being. 

A separate issue is I also have occasional problems with the machine failing to home after losing comms after a timeout waiting for an M400. Afterwards the software seems to think the head is some stupid position outside the soft stops and returns position well to the left (+X) and up (+Y) of the home position.

I have found a workaround for this - resetting the TinyG and physically moving the head by hand to just off the hard stop positions while the tinyG is rebooting gets everything in sync again and the visual homing works fine again. It seems the software remembers where it was and what nozzle it was using between runs after shutdown and if the shutdown is not normal it remembers things that cause problems on the next run of the software. If you can see anything in my Machine.XML that is causing this behavior that would help me a lot too.

[David Glass]

Here is the log of the nozzle probe rubbing during fiducial homing and all a trace of the failure to home issue which has just happened too. I have also attached the very simple job and board files that when run cause the issue with rubbing.

[tony...@att.net]

I haven't had much time to look at this yet but here are a few things I noticed:

Visual Homing Logs:

2021-05-04 19:37:27.845 GcodeDriver$ReaderThread TRACE: [serial://COM4] << Homing error - A axis settings misconfigured

You need to take A0 out of your HOME_COMMAND as the rotation axis can't be homed.  I doubt if that is the cause of your other troubles but it can't be helping.

I think the dragging of the nozzle tip is probably caused by the top camera Z axis being assigned to your physical Z axis "zN1" rather than your virtual Z axis "zTop".  Have you used the Issues and Solutions system?  I'm surprised that would have escaped.

Some other things in your connect command that I'd change:

The $1pm, $2pm, ..., $4pm=2 settings are telling the TinyG to power down your motors after 300 seconds of non-activity (the machine could drift when the motors are not powered) - I think you want to always keep them powered, change those values to 1

You could also clean-up your logs and reduce the usb traffic by adding/changing these settings:

$sv=0

$jv=0

$qv=0

The homing failure log file appears to start immediately with errors from the TinyG:

2021-05-04 19:29:38.326 GcodeDriver$ReaderThread TRACE: [serial://COM4] << {"er":{"fb":440.21,"st":9,"msg":"File not open"}}

This error is typically indicative of the TinyG being in a bad state probably due to something prior to the start of that log file.

You may have something else going wrong getting you into that bad state but I include a \u0018 (backslash-u-zero-zero-one-eight is the unicode escape sequence for the ctrl-x character) as the first line of my DISCONNECT_COMMAND.  That will reset the TinyG every time you hit the disable button which should get it back to a known good state.  Just make sure you have the "Allow Backslash Escape Characters" checkbox enabled on the Driver Settings tab.

[David Glass]

Hi Tony,

I think I have implemented all of your suggestions and I think you have solved most of my problems:-

1. The nozzle rubbing on fiducial homing has stopped

2. The software now recovers from getting into an illegal state without me having to manually move the head.

I couldn't find a DISCONNECT_COMMAND but there is a DISABLE_COMMAND so I tried it in there and now it looks like this:

\u0018 

M9 M5

I have spent most of the day trying to get the other Z heights working. For some reason my Camera - Nozzle offset seems to be off a little now so recalibrated that and that meant going through all the nozzle change positions again.

When I do discard the system reports it can't find sensor A1 and I thought I had switched off vacuum sensing.

I have been having issues with my TinyG losing comms at random times and misbehaving for periods (sometimes days) not just on OpenPnP but also the LitePlacer software too and also on laptops and office PCs so I am forming an opinion that my particular TinyG is not reliable and it may need returning under warrantee.

I am reluctant to do that until I have ruled out it being me misconfiguring it.  I have flashed it with the latest firmware 440.21 but with no improvement.

If you could briefly explain the places where I set the various z offsets and zeros that would help me quite a bit.

Thanks for your help so far.

Here is my latest 

[tony...@att.net]

>If you could briefly explain the places where I set the various z offsets and zeros that would help me quite a bit.

Well that's a rather broad question to answer briefly - can you be a bit more specific?