Performing Tasks When Daq Factory Is Closed

[RLidster]

Hi There

 

Had a little issue..... i have been using DAQ to control a heater in a box and i am looking to use some fail safe features

 

currently the Enclosure on my instrument is controlled with a PID control and this feeds variables into a sequence which determines how much power to apply to a solid state relay connected to a labjack. (how often the SSR is closed and power is applied)

 

the Code all works fine and heats the box and holds it at a set-point very well however we have discovered a problem that if the daq factory program is closed when the SSR is closed (so power is provided to the heater) it stays in this state and so the box gets very very hot!

 

Is there a way to send settings to the labjack if the program is closed (the "x" is closed in the top corner) so it essentially just turns all relays off

 

Best regards

 

Richard

[AzeoTech]

You should never run safety systems through a computer.  Doesn't matter what software or hardware you are using.  Same goes for PLCs.  In your case, I would probably get either a latching thermostat relay and wire it into the power of the heater.  Then, if the temperature gets too high, the relay trips and cuts power to the heater until you manually reset it.  But you'd have to find an appropriately rated safety relay.

 

Disclaimer: This is a general suggestion and in no way is telling you how to handle your application.  Every application is different and we cannot provide exact guidance for safety systems through the web.

 

That all said, you can keep DAQFactory from easily closing by disabling the X:

 

system.hideSystemMenu()

 

and to restore:

 

system.showSystemMenu()

 

Or just run in full-screen.

 

This won't solve the problem, but will make it less likely that someone will quite the application.

 

As for the primary question: the LabJack does what its told and stays in whatever state it was last told.  The exception would be the T7 which has the option to add some basic scripting internally using Lua.  You may be able to script something for this, however, this is not a substitute for a proper safety circuit.

[RLidster]

Thanks for the advice! We had already planned to put in thermal cutouts we were just curious to see what software solutions there might be

 

best regards

 

Richard