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When using the NI SCXI-1127/1128 as a 1-wire 64×1 multiplexer, connect your signals using the NI SCXI-1331 terminal block. In this topology, use the line labeled 1_WIRE_LO_REF inside the NI SCXI-1331 terminal block as the common reference. The following figure represents the NI SCXI-1127/1128 in the 1-wire 64×1 multiplexer topology.
Each signal is routed through the NI SCXI-1127/1128 and is available on OUT0+ screw terminals on the NI SCXI-1331 terminal block, and the reference signal connected to 1_WIRE_LO_REF is routed to the OUT0– screw terminal. You can further route both signal OUT0+ and OUT0– to high-voltage analog bus AB0+ and AB0–, respectively.
During scanning, a typical scan list entry is ch2->com0;. This entry routes the signal connected to ch2 to OUT0+ and signals connected to 1_WIRE_LO_REF to OUT0–. By default, this scan list entry will also route OUT0+ and OUT0– to AB0+ and AB0–.
When using the niSwitch Connect Channels VI or the niSwitch_Connect function with ch2 and com0 during immediate operations, the signal connected to ch2 is routed to OUT0+, and the signal connected to 1_WIRE_LO_REF is routed to OUT0–. To route OUT0+ and OUT0– to AB0+ and AB0–, use the niSwitch Connect Channels VI with com0 and ab0.
The following figure identifies the pins for the NI SCXI-1127/1128 in the 1-wire 64×1 multiplexer topology.
|Caution Do not connect to RESERVED pins or to NO CONNECT pins. Keep low-voltage pins isolated from row and column channels when high voltage is present.|