Re: External Triggering using pci-mio-16e-1

From: <tim.ousley_at_ni.com> · Date: Tue, 17 Feb 2004 16:22:40 -0600

Stefan,

On the PCI-MIO-16E-1 PFI0 serves two purposes as both a digital PFI line
and also as an analog trigger line.  The board powers up using PFI0 as an
analog trigger.  You will need to disable the analog trigger circuitry as
described in 10.8.3 of the DAQ-STC Technical Reference Manual
Analog_Trigger_Control( ).  Since some E-Series models do not have analog
triggering, PFI0 will work correctly on these without explicitly disabling
the analog trigger circuitry.

When I debug this type of issue, I usually trigger off of the PFI2 line
first since it is not affected by the analog triggering circuit.  Then once
I can trigger correctly on PFI2, I disable the analog trigger circuit and
trigger on PFI0.  Finally I enable the analog trigger circuit and trigger
off of an analog signal coming in PFI0.

I don't know the answer to your other questions, unfortunately.

Tim Ousley
National Instruments

                      Stefan Larsson                                                                               
                      <last_at_s2.chalmers        To:       comedi_at_comedi.org                                         
                      .se>                     cc:                                                                 
                      Sent by:                 Subject:  External Triggering using pci-mio-16e-1                   
                      comedi-admin_at_come                                                                            
                      di.org                                                                                       

                      02/12/2004 04:28                                                                             
                      AM                                                                                           

We've been trying to get the external trigger working with the
national instruments card pci-mio-16e-1 without success. After scanning
the mailing list archive we've found out that there seems to be other
people having similar problems.

So far we've observed the following:

1. Sending TRIG_ANY to both scan_begin_src and convert_src and letting
   comedi_command_test() which returns 0x0050 for both which should
   mean that TRIG_EXT and TRIG_TIMER should be the available triggers.

2. We've tried plugging in the TTL-trigger signal into PFI0 and PFI1
   without success.

3. Always TRIG_NOW on start_src (following examples for PFI0)

   Combinations:
     TRIG_EXT on scan_begin_src and TRIG_EXT   on convert_src
     TRIG_EXT on scan_begin_src and TRIG_NOW   on convert_src
     TRIG_EXT on scan_begin_src and TRIG_TIMER on convert_src

   Arguments:
     (CR_EDGE | PFI0) on scan_begin_arg when using TRIG_EXT
     (CR_EDGE | PFI0) on convert_arg    when using TRIG_EXT
    otherwise
                   0  on scan_begin_arg when using TRIG_NOW
                   0  on convert_arg    when using TRIG_NOW

4. cmd.c was used for testing...

5. the read command in vicinity of line 150 (while(1)-loop)
   waits forever when executed
   ( ret = read(comedi_fileno(dev),buf,BUFSZ); )

Does anyone know how to make this work?

* A working example of cmd.c would be interesting to see.
* Any experiences on external trigging would be appreciated.
* In one of the messages in the mailing list archive a
  howto text was mentioned. I have not been able to find
  it. Does it actually exist?

Thanks in advance,
Stefan Larsson and Lars Bergström
Department of Signals and Systems
Chalmers University of Technology
Göteborg, Sweden

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