05-14-2012 04:36 PM
I was wondering if it would be possible to use the SCXI 1124 (on a SCXI 1325) Digital-to-analog-converter as a watchdog timer to verify that LabView is working properly. Basically, I want the 1124 to output a constant (or nearly so) voltage of about 5 V and just a few 100 mA to run a relay. If there is no voltage, then the corresponding equipment shutsdown (or can't turn on in the first place). I know that the 1124 can output this voltage & current combination, and I have succeeded in doing so. However, if I close Labview, or stop the program, a steady DC voltage is still output by the 1124 at whatever the last voltage value was. This is not good. What I want is for the signal to drop to zero if Labview crashes or the PC crashes, etc. Is this even possible with this hardware? If not, is there some other hardware that would work?
05-15-2012 12:01 PM
The SCXI-1124 does not have a hardware watchdog timer, and I'm not aware of any NI analog output devices with this feature. However, there are a number of industrial digital I/O devices that support it: Industrial Digital I/O. I don't know your exact requirements, but some models have high current drive or built-in relays.
Also, there is an idea exchange posting about analog output watchdog timers that you can vote for if you want: Watchdog timer for X Series analog outputs