10-22-2007 08:03 AM
Hello,
I would like to use the Digital I/O USB 6501 as a pulse counter. I know that there is an input (2.7) that can be used for that purpose. However, I don’t know how to use it. I downloaded an example that it’s working fine, the USB-6501 Interactive Control. With that example I can configure all the lines as high/low outputs/inputs, but how can I use the counter? Is there an existing VI for that purpose?
I would appreciate any help.
Thank in advance
Vicente
10-23-2007 05:47 AM
Hi,
The details of the counter on the NI-USB-6501 are as follows:
Number of
counters - 1 (P2.7 can be configured as a
counter)
Resolution - 32 bits
Counter
measurements - Falling edge counting
Maximum input
frequency - 5 MHz
Minimum high pulse width - 100 ns
Minimum low pulse width - 100 ns
I have attached 2 example VIs explaining how to utilise this counter. One file is made using LabVIEW Express VIs and the other file is made using lower level VIs. Both of these methods work, but note that there is more programmatic control of the process using the lower level approach. If you have any questions regarding how the VIs work or anything else, just ask.
Both should open in LabVIEW 8.0 onwards but please let me know if you cannot open the VIs.
Many Thanks,
Ian
Applications Engineer
National Instruments UK
10-23-2007 06:20 AM
Hi Ian,
Many thanks for your examples; they seem to be exactly what I am looking for. I can open both examples but I can’t run them. I get the following error when I open the Low-Level:
Error -200099 occurred at DAQmx Create Channel (CI-Count Edges).vi:4
Possible reason(s):
Physical channel not specified.
Task Name: _unnamedTask<13>
My device is connected and I guess I have the right drivers because the USB-6501 Interactive Control is working fine, so I don’t know what it might fail. I’m not very familiar with tasks; do I need to configure something else?
Thanks for your help
Vicente
10-23-2007 07:22 AM - edited 10-23-2007 07:22 AM
Hi Vicente,
That error just means that you need to specify which counter to use in the programs I’ve sent you (rather than a hardware problem):
Let me know how you get on,
Ian
Message Edited by Ian Colman on 10-23-2007 07:22 AM
Message Edited by Ian Colman on 10-23-2007 07:22 AM
10-23-2007 08:01 AM
Hi Ian,
If I click counter I can only see ‘Browse’ and if I select this I can read ‘Select item/s’ but there is a blank list. If I type the name you sent me I receive a new error:
Error -200220 occurred at DAQmx Create Channel (CI-Count Edges).vi:1
Possible reason(s):
Device identifier is invalid.
Device Specified: Dev1
Task Name: _unnamedTask<7>
Any suggestion?
Thanks for your help
Vicente
10-23-2007 08:29 AM
10-23-2007 08:54 AM
Hi Ian,
Yes, it appears under devices and interfaces. There is a field that says USB devices and if we click there we can read this name:
USB0::0x3923::0x718A::012924F2::RAW
Regards
Vicente
10-23-2007 09:22 AM - edited 10-23-2007 09:22 AM
Let me know if these steps are successfull and as many details as you can if they are not.
Thanks,
Ian
Message Edited by Ian Colman on 10-23-2007 09:23 AM
10-23-2007 10:18 AM
Hi Ian,
I can’t follow your steps. I print you exactly what I can see in MAX:
On the left side it appears my device but I can’t find the ‘self-test’ that you mention. Instead of having ‘Test panels’ I have ‘Open Visa Test Panel’, maybe it’s the same. But, definitely I can’t select your last options.
Thanks for your help
Vicente
10-23-2007 10:38 AM - edited 10-23-2007 10:38 AM
Message Edited by Ian Colman on 10-23-2007 10:39 AM