On 5/10/2013 9:43 AM, Kent A. Reed wrote:
> On 5/10/2013 3:05 AM, andy pugh wrote:
>> On 10 May 2013 03:28, Norton Allen <al...@huarp.harvard.edu> wrote:
>>> In this remote configuration, at the moment I do not have access to the
>>> graphical display. Is there a way to alter the configuration so I can
>>> start up from the command line without a GUI interface?
>> You can, but it might not help.
>>
>> <...>
>> If you can ssh into the remote box then you can just halcmd unlinkp
>> axis.N.max-limit-in (or whatever that pin is called) then halcmd setp
>> axis.N.home
>>
> Norton:
>
> To follow on Andy's "If you can ssh...", what is your overall situation
> here?
>
> Is the remote box running a regular LinuxCNC (or EMC2 if earlier) over
> Ubuntu? If you can ssh into it and if your account permissions allow you
> to execute 'sudo' commands. then you can gain access to the entire
> desktop. Just enable the 'Remote Desktop' on the remote box and connect
> to it with a VNC client on your local box (such as
> "Applications/Internet/Remote Desktop Viewer" from the menu bar on a
> Ubuntu 10.04 box). Ubuntu's documentation of all this is pretty awful.
> Try resources such as
> http://ubuntuforums.org/archive/index.php/t-266981.html.
>
> OK, so the VNC protocol on which Remote Desktop is based can seem as
> slow as molasses in January (do people in the southern hemisphere use
> molasses?), which I expect the tcp/ip packet latency over the multiple
> gateways implicit in a 3000 mile journey exaggerates. Still, I've found
> it helpful where simple command-line access via ssh or single X-client
> access wasn't enough. One respondent in the URL noted above points out
> some alternatives to VNC. It's all a matter of how desperate you are:-)
Kent, Thanks, yes, we have used this system with VNC and it is a stock
installation on Ubuntu (although clearly not the latest.) My inability
to use VNC is temporary and is coupled with the remoteness of the
device. We have operated it successfully with both axis and emcrsh
running, and I have a driver on our main data acquisition system that
talks to emcrsh pretty well.
Why aren't I running VNC now? There was a, um, security problem, and I
killed the VNC server to cut off a remote session. I'm not familiar
enough with Ubuntu and/or VNC to restart it without just rebooting, and
I'm reluctant to do that remotely because the last time I tried that the
system powered off and had to wait for the techs to visit.
>From ssh, I cannot run the emc startup because Axis can't find the
display. Reading through the emc script, I figured out I could set
DISPLAY=dummy, and that worked OK for now, but then re-reading the
emcrsh man page, I see I could just say DISPLAY=emcrsh.
For what it's worth, emcrsh seems to behave much better without axis.
Nonetheless, I'm still having trouble getting this device to home
itself. Even when I virtually disconnect the switches from the limits it
seems the machine seems to be turning itself off during the homing
operation.
Without a power interlock, what conditions will turn the machine off?
>
> A quick Internet search took me to your CV based on which I could hazard
> an educated guess but I wonder if you are at liberty to tell us what
> this linear actuator is pushing back and forth?
Here is a photo:
https://dl.dropboxusercontent.com/u/168018/netcam.jpg
This is an enclosure on the top of a shipping container. The enclosure
covers a solar tracker which directs sunlight down to a high resolution
Fourier Transform Spectrometer for long term monitoring of
concentrations of all sorts of atmospheric constituents. As you can
probably guess, the box slides toward the camera.
>
> Regards,
> Kent
>
> PS - I know this final thought is elementary and I don't mean to be
> patronizing, but all this is easier to work out if you start with a 2-PC
> setup in your lab with one running a LinuxCNC simulator. Both the remote
> access and the LinuxCNC tricks being offered up can be freely exercised
> without danger of borking the remote host.
>
Yes, although I have not visited the site, all the initial testing was
done with scientists and techs on site while I connected remotely. I
could talk on the phone and tell them what I was trying to do, and
they'd tell me what actually happened. The whole system actually worked
pretty well for a few weeks before running into this particular problem.
-N
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