National Instruments NI 781xR - Manual (Page 27)

Chapter 2 Hardware Overview of the NI 781xR
© National Instruments Corporation 2-9 NI 781xR User Manual
Complete the following steps to prevent a VI stored in flash memory from
loading to the FPGA:
1. Power off and unplug the PC or the PXI/CompactPCI chassis.
2. Remove the NI 781xR from the PCI or PXI/CompactPCI chassis.
3. Move SW1 to the ON position, as shown in Figure 2-5b.
4. Reinsert the NI PXI-781xR into the PC or PXI/CompactPCI chassis.
Refer to the Installing the Hardware section of the Getting Started
with the NI 781xR document for installation instructions.
5. Plug in and power on the PC or PXI/CompactPCI chassis.
After you complete this procedure, a VI stored in flash memory does not
load to the FPGA at power up. You can use software to reconfigure the
NI 781xR, if necessary. To return to the default setting so that VIs load from
flash memory, repeat the previous procedure but return SW1 to the OFF
position in step 3. You can use this switch to enable or disable the ability to
load from flash memory. In addition to this switch, you must configure the
NI 781xR with the software to autoload an FPGA VI.
Note When the NI 781xR is powered on with SW1 in the ON position, the analog circuitry
does not return properly calibrated data. Move the switch to the ON position only while
you are using software to reconfigure the NI 781xR for the desired power-up behavior.
Afterward, return SW1 to the OFF position.
Power Connections
Two pins on each I/O connector supply 5 V from the computer power
supply using a self-resetting fuse. The fuse resets automatically within a
few seconds after the overcurrent condition is removed. The +5 V pins are
referenced to DGND and power external digital circuitry. The NI 781xR
has the following power rating:
+4.50 to +5.25 VDC (250 mA max per 5 V pin)
Caution Do not connect the +5 V power pins directly to digital ground or to any other
voltage source on the NI 781xR or on any other device under any circumstance. Doing so
can damage the NI 781xR and the computer. NI is not liable for damage resulting from
such a connection.