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National Instruments Corporation
5
BNC-2121 Connector Accessory for 660X Devices
Connecting to the Spring Terminals
Use the BNC-2121 connector accessory to access the PFI lines on a
660
X
device.
To make the connection, complete the following steps.
1.
Using wire strippers, strip the wire insulation no more than 7 mm.
2.
Connect a wire to a spring terminal on the BNC-2121 by depressing
the orange tab and inserting the stripped end of the wire fully into the
terminal.
Tip
For the best performance, use twisted-pair wire. Connect one wire of the wire pair
from the signal on the peripheral device and the other end of the same twisted wire to the
signal on the BNC-2121. Connect the other wire of the wire pair to the ground of the
peripheral device and the other end to the ground (GND) spring terminal closest to the
signal.
Caution
Make sure that no bare wire extends past the spring terminal. Exposed wire
increases the risk of a short circuit or a failure.
3.
If you need to ground a signal, a ground (GND) spring terminal is
available between every two PFI lines. For details about grounding a
signal, refer to the
660X User Manual
.
The user-defined functions area of the BNC-2121 has six user-defined
spring terminals, USER <1..6>, and six corresponding BNC connectors,
USER <1..6>. Use these spring terminals for either input or output. For
example, if you want to connect a BNC cable to GATE of a counter other
than Counter 0 or 1, connect a wire from the GATE spring terminal on the
660
X
device to a user-defined spring terminal (USER 1) on the BNC-2121,
and the signal is available through the corresponding BNC connector
(USER 1).
The six other spring terminals (ENCODER A, ENCODER B, TRIGGER,
, +5 V, and GND) are used as signal outputs only. Follow steps 1 and 2
in this section to connect the output wires to the appropriate spring
terminals. Use the corresponding controls for each spring terminal, given
in Table 1, to regulate a signal.
Connecting to the BNC Connectors
Use the eight BNC connectors to access PFI <32..39> on a 660
X
device.
Each line corresponds to SOURCE, GATE, OUT, and UP/DOWN of
counter 0 or 1.
