How do I set all Output pins at 0V when Labview is not in use?

[bradle95]

I have a DIO pin connected to a Solid State Relay which controls 115AC. I want to make sure that the AC voltage does not flow to my heater unless I have my Labview Program running and I am sending a high TTL signal to the SSR. This should not be a problem since the user has to flip on a mechanical switch to use the oven, but should someone close the program, and forget to flip this switch off, I want to be sure that the TTL signal will not float high enough to allow the 115VAC to the heater.

In a round about way, I am trying to ask how to I make sure that the DIO pin is at gnd when Labview is not in use. It tends to float around 1.25V. Thanks.

[Process_Systems]

Rather than worry about setting the digital outputs with software, I have used a hardware resettable timer module, with its reset input triggered by a spare digital output. Should Labview stop/fail/or the computer lock up (it is windows, after all!!) the timer will time out without its regular digital reset pulse. Use a contact from the hardware watchdog timer (that is what this is called, BTW) in series with the digital control to shut off the drive to your SSR module.

I am using this any of my projects where I want failsafe operation.

Good luck

Dave