USB DMX P8062-1 query

Kits PC Related Projects
1

Hi, I’ using a P8062-1 kit to send DMX to a project I’m building. On my project an LED flashes whenever DMX values are received within a certain range. I’ve noticed that if I unplug the USB cable from the Velleman USB board and then plug it back in the LED on my board flashes several times. This would seem to suggest that the Velleman board is sending DMX data when powered up even if no controlling software is running on the PC? If this is the case then it makes the board pretty much useless for use in many shows because as soon as it’s powered up all the lights/smoke machines or whatever are likely to go crazy.

Martin.

2

I do not see any DMX data coming out from the K8062 board when the USB cable is plugged in and no controlling software is running.
Here are oscilloscope screenshots of normal operation (software running) and when the board is just powered up (no software running).

3

OK my bad, I’ve done a bit more digging and it looks like when I plug in the velleman boards USB lead my circuit (which is currently being powered from another USB port) resets which causes the LED to flash wierd!

Martin.