National Instruments SCXI: Part 8

This is part 8 in our ongoing blog series about the National Instruments SCXI platform. Part 8 will describe the rack-mountable SCXI Terminal Blocks. If you missed the previous blog posts, you can view them on our blog!

The BNC-2095 and TC-2095 shielded, rack-mountable terminal accessories for SCXI have BNC and thermocouple connectors, respectively. The BNC-2095 and TC-2095 cable to the SCXI-1100, SCXI-1102, and SCXI-1102B/C, SCX-1104 32-channel input modules. You cable the BNC-2095 and TC-2095 to the front connector of the SCXI module with the SH96-96 shielded cable or R96-96 ribbon cable.



The TBX-1303, created for thermocouples, is additionally effective for general-purpose applications. This terminal block has special features for thermocouples, such as isothermal construction with a plastic cover to reduce thermal gradients, open-thermocouple detection circuitry, and automatic ground referencing circuitry. When utilizing the TBX-1303 with the SCXI-1102 Series, this terminal block delivers a high-impedance path to ground, so that systems work dependably with floating or ground-referenced thermocouples. For applications with the SCXI-1100, you can configure the channels to be ground-referenced or floating in blocks of eight channels. For general purpose applications, this terminal block is equipped with 108 terminals, including CH+, CH-, and shield for every input channel. The TBX-1303 works with the SCXI-1181 breadboard module as well.



The National Instruments TBX-1316 is a high voltage attenuator terminal block created to be used with the SCXI-1125, SCXI-1120/D, and SCXI-1126 analog input modules. The NI TBX-1316 extends the input voltage range for AC/DC signals to 1,000 V for Category I installations and 600 V for Category II installations. For voltage measurements, the TBX-1316 is suggested for use with the SCXI-1125 but can be used with the SCXI-1120/D also. For frequency measurements, utilize the TBX-1316 with the SCXI-1126.


The TBX-1325 has 30 screw terminals for signal connections to the SCXI-1124 module. You cable the TBX-1325 to the SCXI module with the SH48-48-A shielded cable. However, keep in mind that the TBX-1325 and SH48-48-A limit the maximum working common-mode voltage between banks or between banks and earth ground to 250 Vrms maximum.


The TBX-1326 is a high-voltage terminal block with 48 screw terminals for signal connections to the SCXI-1162, SCXI-1162HV, SCXI-1163, and SCXI-1163R modules. You cable the TBX-1326 to the SCXI module with the SH48-48-B shielded cable.


The TBX-1328 can be used in conjunction with the SCXI-1120, SCXI-1120D, SCXI-1121, SCXI-1125, and SCXI-1126 modules. The TBX-1328 has 24 screw terminals, including three terminals (CH+, CH-, and chassis ground) for every input channel and sockets for the installation of resistors for 4-20 mA inputs. When used with thermocouples, the TBX-1328 optimizes measurement preciseness with an isothermal construction and a plastic cover that decreases thermal gradients across the terminal block and the subsequent errors.


The TBX-1329 delivers selectable AC coupling for the SCXI-1120, SCXI-1120D, SCXI-1121, SCXI-1125, and SCXI-1126 modules. Every channel of the TBX-1329 terminal block includes selectable AC coupling circuitry that can reject up to 250 VDC. The screw terminals on the TBX-1329 are pluggable.


The NI TBX-24F general-purpose screw terminal block has feed-through connections for 24 signal lines. The TBX-24F can be linked to the SCXI module with discrete wires connected to a regular SCXI terminal block. For example, you can utilize two TBX-24F blocks to terminate the I/O lines for one SCXI-1160 relay module, which needs 48 signal connections (16 relays, 3 lines per relay). You separately wire the TBX-24F to a regular SCXI-1324 terminal block, which attaches to the front of the SCXI-1160 module.


Lastly, the National Instruments BNC-2096 is a 19 in. rack-mountable BNC terminal block for NI PXI-447x, PXI-4461, and SCXI-153x modules. It provides 16 channels of Class I smart TEDS sensor inputs for IEPE sensors such as microphones and accelerometers. The NI BNC-2096 requires digital control from a NI 4021 switch controller or data acquisition device. Two or more BNC-2096 blocks can be controlled by a single device, enabling multidrop configurations for high-channel-count systems.