How to Connect Signals to the SCXI-1161

Overview

The National Instruments SCXI-1161 is a general-purpose switching module consisting of eight independent SPDT (also called Form C) nonlatching relays. They can switch up to 8 A at 125 Vrms, 6 A at 250 Vrms, or 5 A at 30 VDC, making them suitable for higher power applications. Each channel has a normally closed (NC), normally open (NO), and common (COM) terminal. You can use two or more NI SCXI-1161s (and SCXI-1160s) in the same chassis with a single DAQ device or switch controller. The DAQ device controls these SCXI modules through serial communication over the SCXIbus in the backplane of an SCXI chassis. The NI 4021 switch controller or the NI 40470/4060 DMMs control these SCXI modules via the SCXI-1362 cable assembly.

Connecting Signal Wires Directly to the SCXI-1161

It is possible to connect signal wires directly to the terminal block of the SCXI-1161. Picture 1 shows the terminal plugs inside the SCXI-1161. Use the printed labels in front of the terminal plugs inside the module as a guide for wiring your signals.



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The TBX-24F Terminal Block for the SCXI-1161

In Addition to using the terminal block inside the SCXI-1161, you can use an external terminal block to connect your signal wires. The TBX-24F is a DIN-rail mountable terminal block you can use with any SCXI module. It directly connects to the SCXI-1161, which has internal terminal blocks. It connects to any other SCXI module through an SCXI terminal block or direct connections, such as BNC or thermocouple connectors. The TBX-24F mounts on most European standard DIN EN mounting rails.

Connecting Signal Wires to the TBX-24F Terminal Block

Refer to the SCXI module user manual for examples of how to connect field signals and loads. Figure 1 shows the TBX-24F connected directly to an SCXI-1161 module and connected to another SCXI module using a terminal block. Follow these instructions to route the signals through the TBX-24F:
1. Power off the SCXI chassis and the computer that contains the E Series data acquisition (DAQ) device or disconnect the device from the SCXI chassis.

Note: Use insulated wires to connect the TBX-24F DIN-rail mountable terminals to the SCXI terminal block or module.

2. Disconnect all power from the signal sources.
3. Connect the signal wires to the TBX-24F terminal plug that connects to the corresponding terminal for the SCXI module. Refer to Figure 1.


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4. Write the signal names on the adhesive labels and affix the labels to the TBX-24F terminals. Refer to Figure 2.

Figure 2 shows a unique feature of the TBX-24F. There are eight removable terminal plugs so you can disconnect field wires from the system without disconnecting them from the screw terminals. For example, you can remove the terminal plug with field wires intact and connect the field wires to another terminal block or measuring device. The terminal plugs are keyed so that you can insert them in only one direction.

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