Turn on suggestions
Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.
Showing results for
Topic Options
- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Mute
- Printer Friendly Page
SCXI 1001 / 1100 Polling Speed
Larry1234
Member
08-31-2004 12:07 PM
Options
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report to a Moderator
Hello NI,
I am using a SCXI-1001 rack with SCXI1100 channel interface cards to read analog voltages from our lab equipment. Setup of the rack was very straight forward and the rack is working properly.
I read (with moderate comprehension) the SCXI 1100 manual and used your SCXI-1100 Voltage.VI as a starting point for the development of our own SCXI 'channel polling' VI.
In the SCXI-1100 Voltage.VI, there are two parameters
1 - number of samples to average for each datapoint - default 100
2 - number of scans per second - default 200
If I interpret this correcty (and use these defaults), this means that 100 datapoint / 200 scans per sec ===> .5 sec (500 msec) to poll each channel. Can you please confirm that I am int
erpretting this correctly ? If so, my question is, can I poll each channel in the 10 msec/channel range (or possibly even faster) ?
I understand that I need to address the set-up and settling time when measuring each channel. I also understand that I should just try running the rack at the faster speeds. I am not sure what polling rates the SCXI rack will support. I assume it is in the micro second range. I would greatly appreciate your comments as a 'sanity check' for how I am using this device.
Thank you,
Larry Scott
OSRAM Display Engineering
408-456-4072
I am using a SCXI-1001 rack with SCXI1100 channel interface cards to read analog voltages from our lab equipment. Setup of the rack was very straight forward and the rack is working properly.
I read (with moderate comprehension) the SCXI 1100 manual and used your SCXI-1100 Voltage.VI as a starting point for the development of our own SCXI 'channel polling' VI.
In the SCXI-1100 Voltage.VI, there are two parameters
1 - number of samples to average for each datapoint - default 100
2 - number of scans per second - default 200
If I interpret this correcty (and use these defaults), this means that 100 datapoint / 200 scans per sec ===> .5 sec (500 msec) to poll each channel. Can you please confirm that I am int
erpretting this correctly ? If so, my question is, can I poll each channel in the 10 msec/channel range (or possibly even faster) ?
I understand that I need to address the set-up and settling time when measuring each channel. I also understand that I should just try running the rack at the faster speeds. I am not sure what polling rates the SCXI rack will support. I assume it is in the micro second range. I would greatly appreciate your comments as a 'sanity check' for how I am using this device.
Thank you,
Larry Scott
OSRAM Display Engineering
408-456-4072
Bill B
Active Participant
09-01-2004 01:06 PM
Options
- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Report to a Moderator
Hello Larry,
Thank you for contacting National Instruments.
Yes. You are interpreting this correctly. The default scan rate of the SCXI-1100 is set to 200scan/s in this example. The max scan rate of this module is around 166kHz. This is determined by examining the settling time specs. The shortest settling time is 6us. This can be seen on page A-1 of the SCXI-1100 User Manual. Here is a link to the manual:
http://digital.ni.com/manuals.nsf/websearch/0790D3C92CF4B16E8625665E00712865?OpenDocument&node=132100_US
As you can see from the table, the settling time is dependent on the gain setting of the amplifier which is determined by the input range you specify. Please let me know if you need any more information on this issue.
Regards,
Bill B
Applications Engineer
National Instruments
Thank you for contacting National Instruments.
Yes. You are interpreting this correctly. The default scan rate of the SCXI-1100 is set to 200scan/s in this example. The max scan rate of this module is around 166kHz. This is determined by examining the settling time specs. The shortest settling time is 6us. This can be seen on page A-1 of the SCXI-1100 User Manual. Here is a link to the manual:
http://digital.ni.com/manuals.nsf/websearch/0790D3C92CF4B16E8625665E00712865?OpenDocument&node=132100_US
As you can see from the table, the settling time is dependent on the gain setting of the amplifier which is determined by the input range you specify. Please let me know if you need any more information on this issue.
Regards,
Bill B
Applications Engineer
National Instruments
