I need to trigger a 5v relay with DIO USB-6501

[JonShelley]

I'm going to start out by saying that I know very little about
electronics and circuits and parts.  I have the NI-USB-6501 that
sends out 5 volt TTL digital signals.  On the pinout I have a
couple grounds, some I/O channels, and +5 volt connections.  I'm
trying to activate a 5 volt (DC) relay with an I/O channel, but it
doesn't work.  The relay will work fine when I hook the coils
directly to the +5 volt and ground pins on the device, but I can't turn
that on and off via software.  How do I get that strong of a 5
volt signal from one of the I/O channels? (or: how do I feed in the
provided +5 volt line so that it can pass through an I/O channel when
that channel it on and not when it is off?)
Thanks,
Jon Shelley
***@hotmail.com

[Tom W.]

Hi All-
 
I think Buechsenschuetz is on the right track in suspecting that current drive may be your problem.&nbsp; According to the <a href="http://www.ni.com/pdf/manuals/371456c.pdf" target="_blank">USB-6501 Specifications</a> document on page 9, the DIO lines are capable of sourcing only 0.6mA in Open-Collector (i.e. default) mode.&nbsp; You can switch to Active-Drive (aka Push-Pull) mode via an NI-DAQmx Channel property.&nbsp;
&nbsp;
In LabVIEW this is a channel property node as shown here:
<img src="Loading Image...">
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For the C API the necessary function is "DAQmxSetDOOutputDriveType" as described in the NI-DAQmx C Reference Help (Start&gt;&gt;Programs&gt;&gt;National Instruments&gt;&gt;NI-DAQ).
&nbsp;
Alternatively you can add an external pull-up resistor between the output pin and the +5V reference, but the aforementioned setting is recommended.Message Edited by Tom W. on 08-15-2005 12:54 PM


dig drive type.JPG:
http://forums.ni.com/attachments/ni/70/3486/1/dig drive type.JPG

[JonShelley]

Thanks so much guys.&nbsp; I ended up using a transistor (as a switch)
with feeds from the DIO output pin and the +5 volt pin.&nbsp; Then I
had the transistor go to the relay to trigger the 12 volt lights.&nbsp;
There's probably a way to just use a transistor, but for some reason it
wouldn't work with any other power source than the feed from the DIO
device.&nbsp; Thanks again!

[Sileas]

This function (DAQmxSetDOOutputDriveType) does not appear to be available under Linux with NIDAQmxBase 1.5, which appears to be the only thing that works under Linux for the 6501.&nbsp; What are my options?
I'm trying to check continuity through a device (before testing starts) by sending High, then Low, then High from one of the outputs on the 6501, and reading the results on an input on the 6501.&nbsp; I see that I only get a vary brief High on the output, then it falls to low, until I disconnect the output from the input pin.&nbsp;
Any thoughts?
&nbsp;
&nbsp;
&nbsp;

[Sileas]

Unfortunately, this is part of a piece of test equipment, which is required to have no user intervention - just turn on, boot, and run - no GUI desktop or anything (just log in as root and run the program).&nbsp; Is there no way to do this through C or a command line interface instead of having to use the GUI config utility?
Thanks.
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