Accessing the Custom Instrument's Run-time Panel

The host computer is connected to a target Custom Instrument using the IEEE 1149.1 (JTAG) standard interface. This is the physical interface, providing connection to physical pins of the FPGA device in which the instrument has been embedded.

The Nexus 5001 standard is used as the protocol for communications between the host and all devices that are debug-enabled with respect to this protocol. This includes the custom instruments, as well as other Nexus-compliant devices such as debug-enabled processors, frequency generators, logic analyzers, counters, digital IO modules and cross-point switches.

All such devices are connected in a chain – the Soft Devices chain – which is determined when the design has been implemented within the target FPGA device and presents within the Devices view (Figure 1). It is not a physical chain, in the sense that you can see no external wiring – the connections required between the Nexus-enabled devices are made internal to the FPGA itself.

Figure 1. Nexus-enabled Custom Instrument device appearing in the Soft Devices chain.

The GUI for a Custom Instrument used in a design can be accessed from the Devices view. Simply double-click on the icon representing the CUSTOM_INSTRUMENT device whose controls you wish to access, in the Soft Devices region of the view. The Instrument Rack - Soft Devices panel will appear, with the chosen instrument added to the rack (Figure 2).

Figure 2. Accessing the customized instrument GUI.

Note: Each CUSTOM_INSTRUMENT device that you have included in the design will appear, when double-clicked, as an instrument in the rack (along with any other Nexus-enabled devices).