The GX3700/GX3700e can be equipped with the GX3788– Digital and Analog I/O Expansion Module. The GX3788 is a user configurable, FPGA-based, 3U PXI multi-function card which supports digital and analog test capabilities. The GX3788 is based on the GX3700 FPGA card and includes an integral daughter board which provides Analog Input with 16-bit of resolution, 8 differential channels or 16 single-ended channels. Each channel can be set to one of 6 voltage ranges, ±13.60V, ±10.24V, ±5.12V, ±2.56V, ±1.28V, ±0.64V and programmable sample rate of 1 to 75,000Hz. As well as Analog Output with 8 channels, each can be programed to output voltages in the range of ±10V. The module's FPGA is pre-programmed, providing access to all digital and analog functions. Alternatively, users can program or modify the FPGA, allowing user to adapt the module to their own specific test needs. The design of the FPGA employs Intel/Altera’s free Quartus II Web Edition tool set. Once the user has compiled the FPGA design, the configuration file can be loaded into the FPGA directly or via an on-board EEPROM. The digital and analog I/O lines are routed to the 4 front connections (J1 to J4).
The GX3788’s digital I/O signals are TTL compatible and can be programmed as inputs or outputs. There are 32 Differential digital I/O lines, or 64 Single-ended digital I/O lines, supporting Logic Families of LVTTL and LVDS, and configurable for 1.2/2.5/3.3 V logic; 5V compatible, programmable per pin via the FPGA .
The A to D channels can be configured as 8 differential, or 16 single ended inputs and support a sampling rate of up to 75000 samples per sec. The D to A channels support a simultaneous sampling rate of 1 MS/s. The FPGA device supports up to four phase lock loops for clock synthesis, clock generation and for support of the I/O interface. An on-board 80 MHz oscillator is available for use with the FPGA device or alternatively, the PXI 10 MHz clock can be used as a clock reference by the FPGA.
Use the GXFPGA Gx3788xxx driver functions to program the board. The functions are described in detail in GX3788 Functions section. Some of the functions are also available from the software front panel (DAQ page).