National Instruments 777798-01 PXI Multifunction I/O Module

Typically known as the PXI-6025E, the National Instruments 777798-01 is a flexible multifunction I/O module that is intended to provide dependable data acquisition capabilities for a variety of applications, such as manufacturing tests, research, design verification and testing, and laboratory automation. This module offers extensive functionality for a variety of jobs by integrating two 24-bit counters, digital I/O, and analog I/O.

The 16 analog input channels of the 777798-01 module support the following three input modes: differential (DIFF), referenced single-ended (RSE), and non-referenced single-ended (NRSE). Eight channels are available with the differential arrangement, compared to up to 16 channels with the single-ended variants. The circuitry can be configured to scan four differential channels and eight referenced single-ended channels simultaneously thanks to the ability to specify input modes for each channel.

In order to improve the 12-bit analog-to-digital converter (ADC) resolution for accurate measurements, this device has a bipolar input range that varies according on the set gain. Options include 0.5, 1.0, 10, or 100. It also uses a two's complement format for data interpretation and outputs two channels of analog voltage with a fixed bipolar range of ±10 V.

For digital I/O, the 777798-01 contains eight general-purpose lines (DIO<0..7>), which can be individually configured for input or output. These ports have a high impedance when the system first boots up and is reset. In addition, the module has onboard connections for general-purpose counter control, which uses DIO6 and DIO7 to provide up/down control signals without interfering with the DIO lines' ability to function.

With the addition of an 82C55A programmable peripheral interface, which provides an extra 24 digital I/O lines split into three 8-bit ports (PA, PB, and PC), the 777798-01 device's digital capabilities are further expanded. Three modes of operation are available for these ports: basic I/O (mode 0), strobed I/O (mode 1), and bidirectional I/O (mode 2); modes 1 and 2 synchronize data transfers with the help of handshaking signals.

Although settling periods must be taken into consideration, particularly when scanning channels with differing gains, the instrument can scan multiple channels at the same maximum rate as a single-channel rate. In complex installations, this guarantees accurate data gathering.