MAX Device Properties button is disabled / greyed

[tone5]

Hello

I am in the process of commissioning a Labview controlled test rig so am looking for conditions in which the system may become unsafe.

If I simulate a computer/software crash by shutting down Labview (using the windows task manager) the digital outputs remain frozen in their last state before the shutdown. I need them all to become 'low state' (off) because this would make the test rig safe. How can I do this?

Having done some reading, I have tried to set this in MAX, by going to DEVICES AND INTERFACES, selecting the device and then PROPERTIES. However the properties button is disabled / greyed out so I cannot access the properties.

I am using the following software versions: Labview 8.6, MAX 4.7.1 and NI DAQmx 9.2.1

The hardware is: cDAQ NI9178 (chassis) and NI9481 (electromechanical relay module).

Many thanks

[Seth_B.]

Hello tone5,

The NI 9481 doesn't have programmable power up states.  It will always power on with the relays open.  However, in the case you mention, it's not really a power up state issue.  Because the transitions of the relays are entirely controlled by the software, it's not currently possible to change their state without using software of some kind.

Some devices support a "watchdog timer" feature that will return digital outputs to a known state if no contact is received from the software for a certain period of time, but CompactDAQ currently does not support this functionality.  If you feel that CompactDAQ should add this functionality, you may want to post to the Data Acquisition Idea Exchange to see if you can build customer support for the idea.

In the mean time, you'll either need reset the device (Right Click » Reset Device), or use the test panels in MAX to manual open the relays (Right Click » Test Panels), or have a separate application that monitors the status of the first and resets the device when contact with the first application is lost.

Regards,

[tone5]

Thanks Seth B for the answer. I may try your idea of making a second application to monitor the first, which would partially fix the issue. However it's not good news that the power down states cannot be set in the case of a power loss to the computer.

If anyone else has suggestions to acomplish this I'd be interested to know.

Thanks

[Seth_B. · Accepted solution]

In the event of power loss from the computer, the relays will return to their default open state.  Same if the device is disconnected from the computer.  It's in the case where the device is still connected to the computer but the application crashes that you'll need to take another means of resetting the relays.