PFI pins

Howdy all,
      After some more research I figured out that I did indeed want 
subdevice 1, but it needs to be externally triggered which I wasn't 
doing.  When I was doing timer triggering, I was getting 4112 values back 
from each read(), and I'm expecting 12800 per frame.

The Windows code for this device has these two lines:

Select_Signal(device, ND_IN_START_TRIGGER, ND_PFI_0, ND_HIGH_TO_LOW);
Select_Signal(device, ND_IN_CONVERT      , ND_PFI_2, ND_HIGH_TO_LOW);

which I believe are the Windows equivalent (it's using the NIDAQ library 
provided by National Instruments) of setting scan_begin_src and convert_src 
in a comedi_cmd struct.  It's telling them to trigger on PFI pin 0 and PFI 
pin 2.  I tried setting scan_begin_src and convert_src to TRIG_EXT, but I 
wasn't sure what to set convert_arg and scan_begin arg to.  I tried 0 and 
2, respectively, then I tried the constants that ND_PFI_0 and ND_PFI_2 are 
defined as in the Windows code:

#define ND_PFI_0                      	28100L
#define ND_PFI_1                      	28200L
#define ND_PFI_2                      	28300L

But that didn't work either.  Does anyone know how to select PFI pins for 
external triggering in Comedi?

PFI apparently stands for Programmable Function Input, although I don't see 
any evidence of these pins getting configured/programmed in the Windows 
code, so the signal must be coming from the camera I'm trying to acquire 
data from.

Thanks a lot for your help, I'm very new to data acquisition devices, and 
I've been trying to hack my way through it.

Justin

Received on 2003-06-09Z14:28:58