The VXI TTL trigger bus is a powerful component of VXI-based systems and is used to facilitate hardware handshaking between modules, freeing up the CPU for other tasks.
The EX2500 from VTI Instruments is a gigabit LAN-based VXI slot 0 interface, merging Ethernet's architecture and infrastructure and the fast emerging LXI standard for instrumentation with the VXIbus platform.
The EX2500 integrates key features of the LXI standard to create a versatile interface that extends the VXIbus to an external host through the power of Ethernet.
With the introduction of the EX2500A, all eight of the VXI TTL triggers can now be extended across multiple mainframes and to other LXI devices through the LXI Trigger Bus compliant front panel connectors (LVDS). Additionally, the EX2500A incorporates the LXI standard VXI-11 instrument discovery mechanism, simplifying integration within hybrid systems.
The EX2500A is a high-speed gigabit serial communications device optimized for transferring blocks of data in excess of 40 MB/s. A high-performance DMA controller is used during block moves to achieve superior transfer rates. This is accomplished without compromising traditional message-based (word-serial) command performance.
Communication back to the host processor is achieved using a standard CAT5e Ethernet cable. Distances between mainframe and host of up to 200 meters can be realized. A fiberoptic connection is available if even greater distances are required.
Wireless control of VXI instruments is also now possible through the use of wireless routers. Low-cost gigabit Ethernet switches can be used to connect multiple mainframes to a single host. For legacy systems, SMB connectors are provided for single-line trigger input/output as well as external reference clock input/output.
The EX2500A is compliant with the VXIplug&play specifications and implements VISA as the API communication layer. A standard VISA I/O library is included and integrates with either Agilent Technologies or National Instruments versions of VISA. This simplifies installation of the EX2500A into legacy systems using the VISA protocol and preserves any investment in existing TPS and driver development by eliminating the need for costly code modifications.
The VXI Resource Manager is executed automatically at power up time and all system resources are allocated without the need to run a separate utility. The EX2500A runs an embedded web interface and system status including installed VXI hardware, memory allocation, IP configuration and logical address information can be viewed through an .html LXI-style web page. Direct communication to installed devices through message or register-based commands, can be achieved through this interface.