Sampling data

[AzeoTech]

In order for DAQFactory to run in Express mode, you have to include the -runAsExpress flag at startup.  You can put this in your shortcut (see the one we install).  It must go before any .ctl file you list:

c:\daqfactory\daqfactory.exe -runAsExpress "c:\myfiles\myfile.ctl"

 

[Richards]

Is there a formula in a quick sequence of a button to stop (freeze) the traces in the graph.

[AzeoTech]

If you name the graph (select it, right click and select Component name), then yes.  Let's assume you named it "MyGraph":

component.myGraph.XAxisFrozen = 1

Set that to 0 to unfreeze it.  There is a corresponding one for Y, but unless you have the Y axis scaling set to an expression, it isn't really necessary.

[Richards]

I have put that in a button component under quick sequence and it does not work.

component.myGraph.XAxisFrozen = 1 , i have rename ''mygraph''

[AzeoTech]

Can you create a simple document that shows what you did and post it?  (or post your original document)

[Richards]

Here are 2 capture.

[AzeoTech]

I really need to see the actual document.  Email it to our support address if you don't want to post it.  I've attached a simple sample for release 19.1 that shows it.

freezeThawGraph.ctl

[Richards]

I have send the document by Email.

[AzeoTech]

Hmm, we haven't received it.  Did you email to support at AzeoTech.com?

[Richards]

Yes, i have re- Email it.

[AzeoTech]

OK, got it this time.  A number of comments:

1) your Force Conversion has a syntax error.  You have:

Value * 1695 - Value tareOffset

Which makes no sense since there is no operator between Value and tareOffset.  You need to remove the second Value:

Value * 1695 - tareOffset

2) Your Start button Action has a syntax error.  You put two commands on one line.  The two clearHistory() commands need to be on their own lines.

3) your Force and Velocity channels that you are graphing in an XY graph have different Intervals.  DAQFactory will do alignment, but it is better to simply acquire the data for both channels at the same rate.

3) Instead of trying to freeze the graph, I would simply have a sequence do the acquisition.  Do this:

a) put your force and Velocity into a group called Input.  (They are in Main now) and set their Timing to 0.

b) create a sequence called, say PollSensors with this script:

while (1)
   channel.readGroup("Input")
   delay(0.5)
endwhile

c) change the Start button sequence to:

velocity.ClearHistory()
force.ClearHistory()
beginseq(PollSensors)

d) change the Stop button sequence to:

endseq(PollSensors)

This will cause it to only acquire data when pollsensors is running, so when you hit stop it will stop reading the inputs and thus stop updating the graph.  This is better than freezing the graph.

If you want to have force and velocity displayed always, consider adding a second pair of channels with a Timing of, say 0.5 with different names and display them.  They will update continuously, but the two channels you are graphing will only update when PollSensors is running.

[Richards]

Tank you for your support everything is working perfect.

I have and other question : my velocity sensor is a magnet inside a coil, so wen it is going in it generate a positive voltage and wen it is going out a negative voltage.

That is representing a graph with the 0 value in the center like the (graph-2)

i would like to graph like (graph-1).

I am not sure if it is and hardware issue.

[AzeoTech]

I'm not sure, but seems like you can just take the absolute value of the velocity:

abs(velocity)

Or put it in your conversion:

abs(Value) * 1111

(sorry, I don't remember your scaling factor so just put 1111)

[Richards]

I have try it different way , it does no work, wen i put  1111  the graph value is stuck at 1111  .

[Richards]

Is there a formula to invert a DC voltage from neg. to pos.

Let say the voltage comming in from one channel is +0.5V keep it like that.

from the same channel if the voltage is -0.5V invert it to +0.5V .

 

[AzeoTech]

Yes, just multiply it by -1.

Use abs() if you want negative to be positive, and positive to stay positive.

[Richards]

I have put that in the trace X expression and it invert the voltage ,

but the positive do no stay positive.

[AzeoTech]

Then you need to use abs()

So if X Expression is:

voltage

then you would put:

abs(voltage)

 

[Richards]

I have try the high speed streaming as show in section 9.2.2 of the lj AppGuide with no success.

I have include the document .

shock dyno Stream2.ctl

[AzeoTech]

OK, can you provide me more detail about what is happening and what isn't working?  The most common error is to not have the path to the LabJackUD.H set correctly.  It is in line 3 of StartStream.  You will have to figure out where your LabJack drivers were installed and update that path.

[Richards]

Well, wen i start the ''startstream'' it does not start ,no trace.

i have check the path of the labjackud.h, it is in the  ("c:\program files(x86)\LabJack\Drivers\labjackud.h")

i am not sure if the (x86) is important , but it it does not work with that location.

 

[AzeoTech]

Computers require accuracy, especially in applications like DAQFactory that control real world objects.  DAQFactory, therefore, does not make assumptions, unlike, say, the auto-correct on your cell phone keyboard.  So while we read "C:\program files(x86)" and "C:\program files (x86)" and see they are the same thing except for an added space and is just a typo, the computer / DAQFactory does NOT make this assumption and add the space for you.  You have to have it perfect, and you have to correct it yourself. 

The (x86) is also important because we are talking about a path within your computer.  It is most likely that you have both a c:\program files\ as well as a c:\program files (x86)\ folder and these are two different things.

[Richards]

I have copy,paste the link in the sequence , and now , wen i begin the sequence it goes on for a fraction of a second and goes of ,

there's a bit of amelioration. 

[AzeoTech]

The sequence doesn't have a loop in it, so will run quickly and stop.  It should start the streaming and so you should see data in your ChannelA / ChannelB channels.

[Richards]

There is no data ,no trace graphing,

if the sequence  will run quickly and stop, why is there a stop button mention in  section 9.2.2 .