IP cam

[ngoodman]

Hi

I am building a remote monitor and alarm for a remote part of the factory to integrate a lone worker alarm and a remote ip cam.

I have found a bit of perl code to load the camera data into a file this on its own works fine

the plan is to refresh this file and display as a symbol - this works fine from a file

the question is how do I call the perl code to refresh image from within daq factory?

this is my sample code

// capture new picture //

// delete old picture

File.Delete("c:\image.jpg"):

// get new picture

system.ShellExecute("lwp-download http://192.168.8.44/jpg/image.jpg ")

delay(1) // allow time for image to load

// display picture

component.test.loadjpeg("c:\image.jpg")

I think it may be a syntax thing as the "lwp-download" works from a command line

regards

Nigel

[AzeoTech]

Two possibilities:

1) lwp-download is located in the wrong directory. Try fully specifying the path in the shellexecute() call.

2) lwp-download is associated to the perl executor and its either not found, or shellexecute() isn't picking up the association. In that case, specify the executor as well.

I would imagine its probably #1.

[ngoodman]

have also found that lwp-download runs like a batch file. to use it in a batch file you have to use the CALL command and this also works in this application .... correct directory and it all works

thanks

[AzeoTech]

Right. I didn't think about the possibility that it was a .bat file. ShellExecute() works similar to the script in a batch file (since that's what a batch file is, a bunch of shellexecute's essentially), so to run a batch file you have to use call.

[ngoodman]

have found a far more elegant way of grabbing the frame. it uses a dos utility called wget and the program just calls this routine when a frame is needed very simple very reliable.

sequence is below

// capture new picture //


ignore("all")	 // we dont want this sequenceto stop
delay(5)		 // delay to allow network connection 
while(1)
   delay(2)		  //  between pic delay
   getpic=1
   system.DelayUpdate()  // stop screen update
   File.Delete("c:\image.jpg"): // delete old picture

   // get new picture
   system.ShellExecute("wget.exe","open","http://192.168.8.44/jpg/image.jpg","c:\","hide")
   delay(1) // allow time for image to load

   // display picture
   component.test.loadjpeg("c:\image.jpg")
   system.ResumeUpdate()
   getpic=0
endwhile

wget is open source as well (and free) and is available from www.gnu.org/software/wget/

attached is screendump showing image set into top left of screen with controls around

hope this is of interest and help to someone else - I never cease to amaze at the power and versatility of daqfactory - brilliant....

Nigel

[AzeoTech]

Wow, very nice! Thanks for sharing that. I know a lot of people that will be interested, and we'll probably mention it in our next newsletter.

BTW: I recommend using try/catch instead of ignore("all"), even if its just:

try
   // your code
catch()
endcatch

However, I would put ? strLastError inside the catch(). So your script looks something like:

// code
while(1)
   delay(2)
   try
	  // more code
   catch()
	  ? strLastError
   endcatch
endwhile

Note that the delay(2) needs to be outside the try/catch to keep the loop paced correctly even if there is an error.

The reason I recommend this, beyond good form, is that doing ? strLastErrror will at least cause any errors to print in the command / alert window. The sequence will keep running, but you'll actually know something is wrong and what it is.

[AzeoTech]

Also, do you find delayUpdate() is required?

[ngoodman]

Thanks for that

will change error handling as suggested.

I found the image did not always change smoothly from old to new and flashed a red cross for perhaps 1/4 of a second. so used the delayupdate() command to allow time for the image to load. Its pretty much transparent to a user just a slight delay when clicking on a button.

regards

Nigel