Take the following precautions to minimize noise pickup and maximize measurement
accuracy:
•
Use differential AI connections to reject common-mode noise.
•
Use individually shielded, twisted-pair wires to connect AI signals to the device. With
this type of wire, the signal attached to the positive and negative inputs are twisted
together and then covered with a shield. You then connect this shield only at one point to
the signal source ground. This kind of connection is required for signals traveling through
areas with large magnetic fields or high electromagnetic interference.
•
Route signals to the device carefully. Keep cabling away from noise sources, such as
video monitors and analog signals.
Use the following recommendations for all signal connections to the NI PCIe-7846:
•
Separate NI PCIe-7846 signal lines from high-current or high-voltage lines. These lines
can induce currents in or voltages on the NI PCIe-7846 signal lines if they run in parallel
paths at a close distance. To reduce the magnetic coupling between lines, separate them
by a reasonable distance if they run in parallel or run the lines at right angles to each
other.
•
Do not run signal lines through conduits that also contain power lines.
•
Protect signal lines from magnetic fields caused by electric motors, welding equipment,
breakers, or transformers by running them through special metal conduits.
•
To minimize signal-to-signal skew within each digital channel, maintain signal lines'
length within 1 inch of difference.
+5 V Power Source
Use the +5 V terminals on the I/O connector 5 V referenced to DGND to power
external circuitry.
Caution
Never connect the +5 V power terminals to analog or digital ground or
any other voltage source on the NI PCIe-7846 or any other device. Doing so can
damage the device and the computer. National Instruments is not liable for damage
resulting from such a connection.
The power rating is 4.75 to 5.1 V DC at 0.5 A.
On-board Flash Memory
The PCIe-7846 includes a flash memory on-board, allowing users to store their FPGA bitfile
in the flash memory with NI MAX. The user FPGA bitfile will be loaded from the flash
memory after a system power cycle. For more information on downloading a bitfile to NI
FPGA target, visit
dwnbitfile
.
Monitoring the Device Temperature
You can monitor the device temperature through the onboard temperature sensor of the
PCIe-7846 using an FPGA I/O Node. After adding an FPGA I/O Node to the block diagram,
NI PCIe-7846 User Manual
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© National Instruments
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