National Instruments SCXI: Part 2

This is the second part in our series covering the National Instruments SCXI Series. To read the first part in the series, which describes the SCXI analog input modules, click here.

An SCXI system has several parts. One of these is the SCXI-1124 Digital-to-Analog Converter Module. The NI SCXI-1124 is a 6-channel isolated source for DC (low bandwidth) voltage or current signals. The NI SCXI-1124 includes six independently isolated, 12-bit digital-to-analog-converter (DAC) channels. You can configure each channel for voltage or current output. For voltage, choose any of the available three unipolar or three bipolar ranges. For current, each channel outputs 0 to 20 mA. The module is software configurable and includes an onboard EEPROM for storing calibration constants. The SCXI-1124 is well-suited for applications requiring isolated voltage or current outputs to control a process. For more channels, you can use several SCXI-1124 modules in an SCXI system along with other signal conditioning I/O modules. The SCXI-1124 is controlled digitally over the SCXIbus, so a single DAQ device can control several SCXI-1124 modules.



The second analog output module in the SCXI series is the SCXI-1581 Current Excitation Module. The National Instruments SCXI-1581 provides 32 channels of 100 µA current excitation. The high accuracy and stability of these current sources make them especially well-suited for measuring resistance with a high degree of accuracy. The module is ideal in any application that requires a 100 µA fixed current excitation, such as resistive temperature devices (RTDs). You can use the SCXI-1581 with the SCXI-1102 to create a high-channel-count RTD measurement system.



The SCXI-1600 USB data acquisition module can be used in conjunction with either of these modules to create a completely plug-and-play USB data acquisition system. An SCXI chassis is required to house the SCXI-1600 and assorted SCXI modules for a specific system. The SCXI-1000 chassis is capable of holding up to four modules while the SCXI-1001 can hold up to 12.



Another type of SCXI module is digital input and output modules. These include the SCXI-1162, the SCXI-1162HV, and the SCXI-1163 Digital I/O Modules. These modules all have similar features and capabilities with only slight variations. All three modules have 32 channels of optically-isolated digital inputs, arranged in eight isolated banks of four input lines each. The SCXI-1162 interfaces to field digital logic signals, such as TTL and CMOS, where high common-mode voltages can be present. The SCXI-1162HV and SCXI-1163 additionally interface to field digital logic signals. Each of these three modules is programmed by the DAQ device serially over the SCXIbus.


Check our blog for the third part in the National Instruments SCXI blog series soon!