National Instruments SCXI-1000 Schnellstartanleitung Seite 17

3. To determine whether a fuse is blown, connect an ohmmeter across the leads. If the reading is not
approximately 0 Ω, replace the fuse. The fuse marked with a copper + on the backplane is for the
positive analog supply, and the fuse marked with a copper – is for the negative analog supply.
4. Using long-nose pliers, carefully remove the fuse.
5. Take a new fuse and bend its leads so the component is 12.7 mm (0.5 in.) long—the dimension
between the fuse sockets—and clip the leads to a length of 6.4 mm (0.25 in.).
6. Using long-nose pliers, insert the fuse into the socket holes.
7. Repeat steps 3 through 6, if necessary, for the other fuse.
8. Align the fan and filter with the fan holes, making sure that the label side of the fan is face down.
Reinstall the four screws and make sure the assembly is secure.
Refer to the chassis user manuals for fuse specifications.
My chassis worked until I inadvertently removed and reinserted a module while the chassis was
powered on. Now my chassis does not power on. What can I do?
SCXI modules are not hot-swappable, so you might have blown a chassis fuse. If replacing the fuse does
not correct the problem, you might have damaged the digital bus circuitry or the SCXI module. Contact
NI Technical Support at
MAX does not recognize my chassis when I perform a test. What can I do?
Check the following items:
• Verify the chassis is powered on.
• Verify the chassis is correctly cabled to a DAQ device. If more than one DAQ device is installed in
your PC, verify the device selected for Chassis Communicator is actually connected to the
chassis.
• Check backplane pins to determine if any were bent during installation of the modules.
• Verify correct placement and configuration of the modules. If you did not auto-detect modules,
modules installed in the chassis may not be configured in software. Alternately, modules
configured in software might not match the ones installed in the chassis.
All my channels float to a positive rail when I try to take a measurement. How do I correct the
problem?
Make sure that the signal reference settings for the DAQ device match the SCXI module. For example,
if the device is configured for NRSE, make sure that the cabled SCXI module shares the same
configuration. Matching configurations can require a change to the jumper setting of the module.
I am using one of the following modules—SCXI-1100, SCXI-1102/B/C, SCXI-1112, or
SCXI-1125—with one of the following terminal blocks—SCXI-1300, SCXI-1303, or
SCXI-1328—to measure temperature with a thermocouple. How do I stop the thermocouple
reading from fluctuating?
Average the temperature readings to minimize fluctuations. Also, ensure proper field wiring techniques.
Most thermocouples are floating signal sources with low common-mode voltage; they require a path for
bias currents from the SCXI module amplifier to ground. Make sure that you have grounded the negative
lead of each floating thermocouple through a resistor. Refer to the terminal block documentation for
impedance values. For grounded thermocouples, ensure that there is not a high common-mode voltage
present on the thermocouple ground reference.
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17 SCXI Quick Start Guide