TinyG JSON Help

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  • April 27, 2012 at 8:14 am #1933
    alden
    Member

    Mike,

    Thanks for the detailed report. What your symptoms suggest is that it’s most likely the serial stream is getting corrupted, and this is most likely a problem in the end-to-end operation of XON/XOFF. What the machine does after the serial stream becomes corrupted is quite random and unpredictable, so not much information there.

    I (re)confirmed that I am able to run the shapeoko hello world file you provided on my setup. It runs successfully. I also confirmed that you have XON/XOFF enabled from your settings. You do. So what this tells me is that it’s probably not a problem in the TinyG code, but in the upstream serial interface and/or driver.

    There are some significant differences between our host environments:
    – I’m running MacOSX Lion, you are on XP.
    – I’m therefore running a completely different set of FTDI drivers than you are – you are running FTDI driver version 2.8.14.0
    – I’m therefore running the Mac version of Coolterm not the Windows version

    So over the weekend I’ll try to replicate your setup as closely as possible on a Windows box I have lying around. Some questions:
    – What kind of machine are you running?
    – Do you have any information on the serial port and the serial drivers. See
    My Computer/Control Panel/System/Device Manager/ Ports for info.
    – What service pack are you up to on XP and what type of XP are you running – home? pro?
    – What version of Coolterm are your running?
    – Just for yuks, what COM port does your USB driver map to (although this is usually quite random)?

    – Lastly, what is the behavior of the XON/XOFF LED? It’s the OUT3 LED located right next to the resistor labeled R22 in the picture here:
    http://www.synthetos.com/wiki/index.php?title=Projects:TinyG-Hardware-Info:#Interface_Pinouts

    — Does it flash on and off during operation?
    — When the machine goes OC is it on or off?
    — Does it not turn on at all?

    The LED turns ON when XOFF is issued by the board (because the serial receive buffer hit it’s hi threshold -about 200 out of 256 characters), then turns OFF when XON is received from the host. Being stuck in the ON state can indicate that the board received characters, hit the hi limit of the buffer, issued the XOFF, then never received an XON. What THAT usually means is that the host never acted on the XOFF and just continued to jam characters down the wire.

    I’ll reserve judgement until we confirm or eliminate XON/XOFF as the culprit, but we are finding that even though our setups work fine with XON/XOFF, some others don’t. Rather than diagnose each XON/XOFF problem independently the tgFX code synchronizes on the command responses rather than relying on XON/XOFF. So bear with us a bit longer until we get that out. In the mean time, let’s try to get to the bottom of your issue.

    – Alden

    UPDATE: Can you please confirm the release of the FTDI Drivers you are running? in the VCP driver section I only see version 2.08.24 for for the Windows x86 – 32 bit. I do not see any drivers labeled 2.8.14.0 – perhaps you are running an earlier version.

    Also, please also confirm that you are using the VCP drivers and not the D2XX drivers – I have to assume that you are because otherwise you don’t get a COM port, but let’s just be sure.

    Thanks

    April 27, 2012 at 4:55 pm #1934
    alden
    Member

    So I’ve set up a real Windows environment with Windows XP Professional version 2002 Service Pack 3 and tried to reproduce the issue, but unfortunately the Windows setup runs without a hitch. I am using the latest FTDI VCP drivers (version 2.8.24) – which may be newer than yours, and CoolTerm Win 1.4.0 (build 157) – also the latest version. I can run the entire Shapeoko file on Crocs build 326.06. I am also running a TinyG config that is identical to yours except that it seems all my motors run in the opposite direction from your so the polarity settings are all different.

    So lets try to figure out what’s different in the setups.

    One thing I noticed was that you are running the Shapeoko with VERY conservative configuration settings. It’s capable of moving a LOT faster and being a lot more responsive. Below is a comparison of what I’m running for TinyG on the Shapeoko.

    – You have Motor 1 (X axis) set to 1.8 degrees per step. Motors 2 and 3 are set to 0.9 degrees per step. Is this right? Seems they should all be 1.8 or all be 0.9. My settings are 1.8 degrees per step (200 steps per revolution).

    – I measured 34.5 mm per revolution, you have 35. You may be right., I need to check my measurements.

    – As I mentioned earlier, our polarities are different, but this should be of no consequence. I assume you already know that is the convention for the X axis to move positive to the right, for Y to move positive away from the front, and Z to move positive upwards.

    – Your Seek Rate (which has been more accurately renamed to “Velocity Max” in 0,93) is set to 12000 mm/min for the X axis but is 600 for Y and 500 for Z. My settings are X=16000, Y=16000, Z=1200. These are admittedly very fast, and may require some mechanical tweaking to achieve. A good starting point would be 10000, 10000, 1000 until you are sure these work for you.

    – Your feed rates should equal your seek rates – at least for testing. If you run some heavy material through the machine you may want to drop these to a speed where you still get good cutting. This may vary from job to job depending on the material you are cutting. The velocity max should not need to change.

    – My Jerk max values are 5 billion – you have 50 million. This makes a huge difference in acceleration speeds. If you get stalls, back off from this – try 2 billion, or less

    – My junction acceleration is 200000 – you have 50000. The related value: cornering delta (renamed “junction deviation” in 0.93) is the same as yours at 0.05 for all axes

    The rest is probably fine. You will get much better performance from the system with different settings. But first let’s figure out the immediate issue.

    – Alden

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