stop event

[Steve2571]

Hello all,

Is it possible to run a custom VI after the stop button has been pressed in Signal Express?

I have the desired functionality working with a conditional repeat loop, but the data logging does not work.  Therefore, I am wanting to know if there is some sort of stop event in Signal Express we could use.

Thanks,

Steve

[HeatherBaker]

Hi Steve,

Can you please clarify the issue?  I cannot tell if this is one question or two. What data logging does not work?  What version of Signal Express are you using?

[Steve2571]

Sorry for the cryptic message.  I was going on 4 hours of sleep that day.

We are using LVExpress 2009.  I figured out the issue with the datalogging not working in the conditional loop.  Apparently, I had inadvertantly enabled some start criteria in the recording options.  Once that start criteria was removed, the data logging works fine.

The original question I had though was really concerning a stop event when the user presses the stop button.  I have  a test running where the several channels of thermocouple data and pressure transducer data are being acquired.  We have writtent the LVExpress program to monitor one of the thermocouples and if the temp falls outside our predefined range the test will shut down.  We are doing this via a limit test in LVExpress.  The physcial test is endurance testing of an industrial gas compressor.  The hardware we are using is a 6024E daq card connected to a SCXI 1000 chassis with a couple of the 1102 modules and one of the relay modules (I forgot the NI number of that module).

When the LVExpress program is started it begins to acquire data and also turns on the electric motor used to drive the compressor via control of a variable frequency drive.  The LVEXpress program performs the limit test and if the temperature is within the acceptable range it sends a boolean true signal to a custom LV vi that has been inserted into the LVExpress project.  If the temperature is outside the acceptable range it sends a boolean fals.  The custom vi is nothing more than a small daq assistant vi that open or closes channel 1 on the relay module within the SCXI chassis.

The issue arises when a user clicks the stop button.  Prior to implementing and fixing the issues involved with the conditional loop, if the LVExpress program was run continuously if the stop button was pushed the motor on the compressor would continue to run because the relay remained in the "on state".  I tried to incoporate an operator interface using a switch, but the swicth would not bind itself to the inputs on the custom vi within the LVExpress project.  Therefore, I was wondering if there was a stop event that is raised when the stop button is pushed.  If so, I could include my custom vi such that it would shutdown the motor.

My ultimate work around was to use a conditional loop.  This worked well as the loop would acquire and log data continuously until either the limit test failed or the stop button was pushed.  Once execution exited the conditional loop, it would goto my custom vi which would switch the relay and turn of the motor prior to the end of the project.

However, while I do have a work around in place I am still curious if there is a stop event where code could be placed once the stop button is pressed within LVExpress.

Thanks,

steve

[HeatherBaker]

Hi Steve,

I am glad that you have a working solution and I looked into your question a little more.  Using an Operator Interface is about the most you will be able to interact with Signal Express.  I was unable to find any information about a stop event in Signal Express that you could use with LabVIEW.  This appears to be a limitation of the program.