trickyrick said:
Can some one give me a little info about usb controllers I have being
looking on the net and Im not sure what I should be looking for
I want to control about 8 relays through my USB port and would also
need some kind of software program that comes with it.
Has anyone purchase anything like that lately
Thanks Rick
Are you talking about having a stand-alone controller that communicates to the PC via USB (i.e., your actual control software is on the end of the USB line), or just an I/O device that communicates over USB, (i.e., your control software resides on the PC)?
If the latter, such as National Instruments USB6501, then look at page 6-12 of the follow PDF for the type of information you should be looking for:
http://www.ni.com/pdf/manuals/371456f.pdf
-> over voltage protection
-> Max current/power
-> pull-up resistor availability
-> signal level (TTL?)
-> thru-put (how fast can you switch the attached relays
-> isolation (depending upon what load your relays are attached to,
it's likily that you'll need an external power supply and thus
will want some isolation from the PC.
I've used NI's USB6501 to switch transitors connected to two lamps that pulled 110mA each. I was using the USB to power the lamps and couldn't do much more with the 0.5amp USB current limit. (LEDs were not bright enough).
