National Instruments 781157-01 USB CompactDAQ Chassis

National Instruments designed the 781157-01, a four-slot USB CompactDAQ chassis, as a member of the cDAQ-9174 Model range. With its plug-and-play USB interface for sensor and electrical measurements, this chassis acts as a basis for the construction of compact, portable sensor measurement systems. A wide range of measurement capabilities are made possible by its ability to streamline timing, synchronization, and data transfer between C Series I/O modules and an external host.

Users can utilize compatible C Series I/O modules with the 781157-01 chassis to build a combination of analog input/output (I/O), digital I/O, and counter/timer measurements. The chassis offers flexibility in measuring activities with its four 32-bit general-purpose counters/timers, supporting up to seven hardware-timed processes at once. Furthermore, three separate analog input rates improve timing accuracy.

In order to provide crucial feedback on USB bus communication and operational readiness, the chassis contains two status LEDs: READY and ACTIVE. Making use of a Hi-Speed USB 2.0 interface, it guarantees effective data transfer and, through a locking mechanism, relieves strain on the USB cord.

The 781157-01 module interface’s key characteristics include autodetection, signal routing, synchronization, and management of data flows between the STC3 and C Series modules. Included in the interface, the STC3 has the ability to trigger, support PFI signals for multi-device synchronization, and provide independent high-speed data streams with adjustable sample timing for analog input/output.

Analog input functionality includes a FIFO size of 127 samples per slot, variable sample rates determined by the C Series modules, and precise timing accuracy of 50 ppm with a resolution of 12.5 ns. With integrated regeneration, analog output can enable hardware-timed operations for up to 16 channels at a maximum update rate of 1.6 MS/s. Waveform creation and acquisition are included in digital waveform characteristics, with clock frequencies and FIFO sizes adjusted to suit specific application needs.

Digital triggers, which can be obtained from any module PFI terminal, enable the user to select the polarity of most signals for a variety of applications through software. These triggers improve measurement control and flexibility of the 781157-01by starting processes involving analog input/output or counter/timer operations as needed.