stop recording

[jtm]

I have a SCXI-1000 with a SCXI-1600 monitoring voltages with a SCXI-1120 and a SCXI-1327. I am hooked up to 125vac on all 8 inputs. I would like to be able to stop recording if one of my signals goes to 0vac(or close to it) and stays there for x time.

Due to the AC voltage going positive and negative all the time I can not seem to figure out how to do this. Even if I could get an alarm when this occured it would be helpful.

Thanks.

[Bueller]

Hi,

One way to determine time is by counting the number of acquired samples and multiplying it by the period=1/sampling frequency.

If you are continously acquiring, let x be the number of samples that correspond to that cetain time delay you are looking for. The way your program should go is that if you read x consecutive samples whose amplitude lies within that range you are looking at, then you can stop the program.

That might be one possible way of approaching this issue. If you are using LabVIEW as the software, check the "Acq&Graph Voltage-Int Clk-SW Trig Restarts.vi" . You can find it in LabVIEW  in Help >> Find Examples >> Hardware Input and Output >> DAQmx >> Analog Measurements >> Voltage

Regards,

Faris A

[jtm]

Thanks for the reply but I am only using Signal Express. I do not believe Signal Express has that capability.

My goal is to record these signals. When one of them goes low ( I will not know when it is going to go low and will not be viewing it) the recording will stop (after a few seconds). This way I can go right to the end of the recording and view which signal went low first.

[Bueller]

You can add a trigger step in LabVIEW Signal Express. The trigger step is found under execution control.

Signal Express Help is a very useful resource on using triggers.

Regards,

Faris A

[jtm]

I have read through the help document multiple times and still can not see how I can trigger an alarm. I want to trigger the alarm or stop recording x amount of time after any of my signals stay low for x time. Because I am reading AC signals I can not figure out how to set up the trigger. 

[Bueller]

Hi,

If it's only for recording purposes and just setting alarms, you can use the recording TAB and set whatever start and stop conditions.

Please check the attached snapshot.

Regards,

Faris A