How to stop and restart a measurement with a specific criteria?

[celsosilva]

Hey guys,

I'm burning my brains trying to figure out this problematic on my program.

For my research project I am using an O2 sensor that is coupled to a Labjack U12 card and therefore I am getting a constant value of 4 mg/L based on the switch on/off of a AC power plug (connected to the analog output) that is connected to the aeration system. So when I have 3,8 mg/L switches on the aeration and 4,2 switches off.

But I want to run this measurement for a specific time (maybe 10 min) and then stop the signal to the analog output. After sometime the O2 measurement will drop to values of 0 mg/L but I want that when it reaches a specific value (maybe 0,5 mg/L), stays still inactive for a specific period of time (maybe 2 min) and then activates again the signal to the analog output (cycle restart).

Is it possible to stabilish this concept using Dasylab? I would so grateful if you could help me with that!!!

I'm attaching 2 pictures, one from my actual block configuration at Dasylab and the other is the expected measurement after the new configuration.

Hugs and looking forward for suggestions,

Celso 

[MHa]

@celsosilva,

I think that the DASYLab addon "Sequence Generator" should be useful for this task. More details under http://www.mccdaq.com/daq-software/dasylab-upgrf2p.htm

Best regards,
MHa

[hw70 · Accepted solution]

Is the curve in the diagram the output of the "Labjack: Ai"-module?

Then you can use the following block-series:

Direct the signal from the Labjack-in-block into a combitrigger-block: Start-event is when the signal drops below 0,5, Stop-event is when the value rises above 0,5 (do NOT use events "is lower than"/"is greater than"!).

Connect the trigger-block to a counter-block, that counts the time the received signal (from the trigger-block) is TTL-high.

Use another trigger-block right after the counter-block: Start-event is when the signal rises above {insert time in seconds}, Stop-event is 'Direct'.

Now connect an action-block, that controls the corresponding aeration-switch (turn on: curve rises, turn off: curve drops -- is this correct?!), the action should fire, if the received signal from the previous block puts out a rising edge.

How to control the 10min-measurement-time with counter-, trigger-, switch-, and action-modules is left as homework. 😉

[celsosilva]

the curve in the diagram is not the output of the ""Labjack: Ai"-module".

The output of the Labjack: Ai"-module just gives a signal to the AC power plug that is connected to the aeration system. I am not sure if your configuration is going to work but i will try it tomorrow but many thanks for the help 🙂

Do you know if it is possible to connect the action-block to an TTL-Pulse generator (that is connected to the relay-block) and after the expected 2 min it resets the TTL-Pulse generator (even if the Phase 2 is still not finished)??

[celsosilva]

It did work!! 😄

I tried the block-series: trigger-, counter- , trigger, -action and worked perfectly!! To solve the 10 min measurement time I used a TTL Pulse generator with 10 min Phase 1 connected to a relay. So when the sensor reaches values of less then 0,5 starts a countdown of 2 min and then the action-block resets the TTL Pulse generator and a 10 min measurement starts again.

Many thanks to the member hw70 😄 

[Tiger진]

Sorry, I can't  write new message, so I write here.

I have a same problem but little diffrent...

I'm trying to get a singnal Lateral accelation using car.(50~90KPH, radious-100m)

Data aqusiton region is 20m

My task is get a specific region of data (9.9~1.1m)

I attemped to using on/off triggring but I couldn't find the answer..(it has not a input condition)

is it possible?

-Dasylab 9.0 : Tool
-Iotech Daq book 100 : DAQ board

-accelerometer : accelation

-VBOX(recelogic) : velocity

[Tiger진]

missed attach..