switching a relay via USB

We do it at work over that sort of distance with a USB-to-Cat5 converter. Seems to work OK, but only at USB1.1 speeds. However, that's plenty fast enough for a relay ;-)

For this job though, having the switching closer to the PC and using Plain Old Volts to carry the signal to the gates seems like a better bet... something like the USB-RLY08 for £40+Vat from would do it nicely.

I'm assuming you could pick up the 24V from the gate end, so this would only need to be a switch.

Why are you assuming the USB will be extended to 150m rather than the wires to the relay? It is easy to make a relay operate over 150m of cable.

snipped-for-privacy@t13g2000yqt.googlegroups.com...

Why are you assuming that I made such an assumption?

Why can't you comprehend "USB isn't good for 150m unless you cascade loads of hubs"?

I didn't make any assumptions about anything.

MBQ