Velleman VM138 Bedienungsanleitung Seite 9

Manual Override Function:
Exceptionally, the relay must be activated, even when there is no DMX signal (e.g. when testing a light bulb).
Proceed as follows:
Position the DMX address to 0
Mount jumper JP1
Switch on the 12V power; the relay will activate regardless of the DMX value.
DMX channel
9