Hello Phooi,
I'm not exactly sure what could be causing the behavior you are
seeing, but the first place to start would be to verify that your
system is installed and configured correctly. When working with
both analog and digital SCXI modules, you must use the analog module as
the communicating module because it can transfer both analog and
digital signals from the SCXI bus to the DAQ device. I am
assuming you are connecting the SCXI system to your NI PCI 6251 with a
68-pin cable connected through an SCXI 1349 adapter into the back of
one of your modules. Make sure that the module that you are
connecting to is your SCXI 1102 and not the SCXI 1161.
The next thing I would try is to re-configure your system in
Measurement & Automation Explorer (MAX). Anytime you make a
change to the hardware in your SCXI system, you need to rescan for
devices in MAX to reconfigure your changed system. Here are the
basic steps for configuring your SCXI system:
1. Under 'My System', expand 'Devices and Interfaces'.
2. Right-click 'NI-DAQmx Devices' and select Create New >> NI-DAQmx SCXI Chassis and select your chassis.
3. Under the 'Modules' tab, autodetect your modules and select the accessories associated with each module.
4. Under the 'Chassis' tab, select your NI PCI-6251 as the
'Chassis Communicator' and select your SCXI 1102 as the 'Communicating
SCXI Module Slot'.
5. Click 'OK' to save your changes.
You must re-autodetect your modules and re-configure your chassis
communication settings every time you make a change to the hardware in
your system.
My final thought is that you might have blown a fuse in your SCXI
chassis. There are two sets of fuses in the chassis: one
associated with the main power for the chassis, and another protecting
the analog circuitry in the backplane of the chassis. If the
first fuse is blown, you will not be able to even power on your
chassis. If the second set of fuses (protecting the analog
circuitry) are blown, you will still be able to power on and autodetect
your modules, but you will not be able to acquire any analog input
data. SCXI modules are NOT hot-swappable, i.e. you need to power
down the chassis before plugging in or removing modules from your
system. Swapping SCXI modules with the chassis powered on could
have resulted in a blown fuse and the behavior you are seeing. A
blown fuse is not that serious and can be replaced by you without
having to send the chassis back to NI for repairs. Here is a link
to a knowledgebase describing how to diagnose and fix blown fuses in a
system.
KnowledgeBase 29EHH5SV: SCXI Fuse Information
In conclusion, try starting from scratch and fully reconfiguring your
SCXI system in MAX. If that does not work, investigate the status
of the fuses in your chassis for signs that they might be blown.
If none of these suggestions solves your problem, post another reply to
this thread with your progress and hopefully we can get you up and
running.
Regards,
Travis Gorkin
Applications Engineering
National Instruments
www.ni.com/support
