How to shut down without sending random DMX messages

This seems like a fixture issue. look in the manual for the fixtures and see if there is a hold mode. A hold mode is a mode that will hold a fixtures last Dmx value. This will prevent the fixture from going into sound active mode when dmx is lost.
Sincerely,

Some fixtures just go into a random mode when they lose DMX signalling. This should not be thought of as a sign that the fixture is cheap or low end though, although it is more often found in lesser expensive fixtures.

However, to have to hard reset the lights to resolve this problem sounds like a bigger issue. Of course, you're going to have to power cycle your entire truss to fix that problem. It sounds like if DMX signal is lost, they go into master/slave mode. Typically though, they come out of this mode when DMX signal is detected. At least a lot of stuff behaves this way.

I have American DJ and Chauvet products in my rig. Fortunately, my Chauvet fixtures don't go random on me when they lose DMX signal, they just sit and wait. Of course, my 2 movers go into a full reset sequence once they get DMX signal to them even if they already went through it on power on. My other lights just sit and wait. Similarly, all my ADJ DMX stuff also stays in DMX mode and waits.

In the end, read your fixture manuals and see what options you have. As far as shutting down MyDMX, I agree with how you're doing it: issue a blackout command and then exit the program.

I need to go back and run it through the whole shutdown procedure a few more times to troubleshoot. Here's what I do, and I need to pinpoint where in the sequence the scanners go mad:

1) Issue a blackout command which, for my purposes, is not all to zero- usually my "blackout" centers the pan and tilt (value 127), and leaves the shutter open (value 6). Should I try an "everything to 0" blackout command? Usually DMX fixtures just stay wherever they just were.

2) Close the MyDMX program.

3) Click the icon on the task bar and eject the dongle device.

4) Unplug the dongle.

5) Shut down/close the laptop.

I'll have to try them out with a hardware controller to see if I can rule out MyDMX.

While on topic- do you guys leave your DMX fixtures on all the time, or do you kill power to them if they won't be used for a while? I'm going to be using these for theatre and concert purposes, where I will often set up lights the day before or even several days before. I just don't know if I should leave them powered up and waiting, or if I should power them down at the end of the night.

Okay. I think I have it nailed down.

1) The problem occurs exclusively when I hit step 4 of my above post- unplugging the dongle.

2) The problem seems to only occur when some DMX value was above 0 prior to shutting down MyDMX, even if that value was tilt/pan or shutter.

3) The reason the problem could not be overridden is still eluding me as I can't replicate that specific problem anymore. My theory is that the random DMX value received by the fixture put it into another display mode that would not be affected by my values or even the reset. Every time since then, reset has solved the issue.

4) I can completely avoid the issue by treating the laptop/dongle like a hardware controller and simply unplugging the DMX cable from the dongle prior to unplugging the dongle.

My working theory is that unplugging the dongle sends some junk data up the line that the fixtures interpret as random DMX values. This might be caused by Windows 7 still supplying power to USB even after ejecting the device, as opposed to prior versions, which stopped supplying power when devices were ejected.

The important thing, in any event, is that I've figured out how to shut down the computer without having to power cycle the lights.

A word of advice:

Don't do what you're doing or you may damage your hardware. The DMX cable should be plugged into the hardware before connecting via USB(in an ideal world) and then removed after being disconnected from USB.

I am front-ending my DMX after MyDMX or Compu Show with an Elation Opto-Branch/4, which ensures nothing nasty comes back at me from the lighting. It's inexpensive for what it does anyways.

That's my recommendation. Plug in DMX, plug in hardware, run MyDMX. When done, exit myDMX, unplug hardware from USB, disconnect cable.

In the meantime, make a "power off Blackout" scene of all ZEROs. Just make a new scene, it will default to all zero values, name it "POWER OFF" and then that's the last thing you run.

That makes sense, and it did seem to work when I tried it before, but how could unplugging the DMX cable (after closing MyDMX and "ejecting" the device) do damage?