Re: NI PCI-6025e counter problem

From: <tupperfungus_at_netscape.net> · Date: Fri, 10 Feb 2006 22:05:07 -0500

Hi Jordi,

The functions you gave worked perfectly pretty much right away. The 
example program was very helpful as well.  Thanks a lot for taking the 
time to share all of it.

Thanks again,
-Leon Aksman

-----Original Message-----
From: Jordi Blanch Carles <jordi_blanch_at_encopim.com>
To: tupperfungus_at_netscape.net
Cc: comedi_at_comedi.org
Sent: Fri, 10 Feb 2006 09:51:16 +0100
Subject: Re: NI PCI-6025e counter problem

  Try to use these files. We had success with them one year ago.

  In order to have positive and negative counts when the encoder counts 
up or down, we initialized the counter at the half of it's total count 
(2^23) and then substracted the same value after returning the result 
in our reading function.

 Hope it helps

  El dj 09 de 02 del 2006 a les 16:35 -0500, en/na 
tupperfungus_at_netscape.net va escriure:  Hi,

I'm trying to figure out how to use comedi to read from one of the two
counters on the NI PCI-6025e board.
I've tried using:

comedi_data_read(device, 4, 0, 0, AREF_GROUND, &data)

since i know it's the fifth subdevice on the board and I want to read
from the first channel using the only available range for the subdevice.
On the hardware end, I've got a two channel (A and B) encoder that I
convert to CLK and UP/DN signals using an LS7084 chip (very similar to
LS7184) as explained in the NI website's "Using Quadrature Encoders
with E Series DAQ Boards" at:
http://zone.ni.com/devzone/devzoneweb.nsf/Opendoc?openagent&36BD71244BB26

FC886256869005E541B

I'm connecting the LS7084's CLK signal to the board's PFI8/CTR 0 SRC
line and the UP/DN signal to the P0.6 line. I've checked the two
signals coming out of the LS7084 and they seem to be functioning
correctly.

The problem is that the value I get from the comedi_data_read call does
not change (it's a large number on the order of 2^24, which is
encouraging since the counter is 24 bit). The signals coming into the
board do not seem to be incrementing the internal counter up or down.

Am I doing something wrong either in how I'm connecting these signals
(do I need to do something with the CTR 0 GATE line as well?) or am I
not setting something up properly on the comedi end?

Any help would be greatly appreciated.

Thanks a lot,
-Leon Aksman
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Jordi Blanch Carles
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