Components

• Main-controller board and routing matrix for NEXUS STAR routers
• Controls and monitors all components of NEXUS Base Devices
• Organizes routing and sync functions plus clock generation
• Handles up to 16 lines with 256 inputs and 256 outputs each
• Transparent forwarding of 30-bit audio
• Stores the current system status separately from the control computer
• Operation and status indicator LEDs
• Clock generation plus synchronization to various sync sources
• Connects the system to control computers (RS232/422, USB, or Ethernet)

The RCX integrates two functions of the NEXUS STAR router on a single board: the main CPU formerly contained on the RCPU board and the audio-routing matrix, which used to be on the RMX board.

The RCX as the central control unit is a mandatory component of the NEXUS STAR router.

The NEXUS RCX and XCPU boards are the basic components of large NEXUS audio networks. The combination of a NEXUS STAR central router and distributed NEXUS Base Devices offer an overall matrix capacity of 4,096 × 4,096 crosspoints — more than 16 million crosspoints in total.
The number of sources and destinations can increased still further by cascading multiple NEXUS STAR routers.

Like with the NEXUS system, all volatile data of the RCX board is stored to battery-backed SRAM. This ensures that the most recent status can be recovered after power failure or shutdown.

CPU Functionality

The CPU handles communication with external control computers, system management, and control and monitoring of all system components including the router backplanes and the power-supply units. Connectivity to control computers is provided via two RS232/422 ports, one USB port, or one Ethernet port (10/100).

Synchronization and clock generation are achieved using a PLL with extended time constant to provide a low-jitter system clock. Standard sample rates of 44.1, 48, 88.2, and 96 kHz are supported. (Other rates are available on request.)

The CPU features a wordclock input for external synchronization and a wordclock output sending the synchronized internal clock. The following sync sources are available: internal source, the word-clock input, any digital input (including inputs from NEXUS Base Devices), any optical input, the optional RSYNC board (video, WCLK, AES/EBU), and MADI (RMF) if available.

The CPU not only provides control functions but also monitoring features. It continuously monitors the battery status and checks for device failure. A thermal sensor is mounted on the RCX board and continuously monitored by the CPU.

The firmware is stored in a flash memory soldered onto the CPU and can be updated using a utility program running on the PC. No physical components need to be replaced for this purpose.

Router Functionality

The audio-routing matrix is adjacent to the CPU on the RCX board. It is the switching center for all audio signals on the NEXUS STAR. In contrast with the bus structure in a standard NEXUS system, here the audio is transmitted using an active routing matrix.

The audio-routing matrix manages all audio channels of the up to 16 audio- interface boards that can be installed into a NEXUS STAR. It makes 256 inputs and 256 outputs available to each of the interface boards, thus providing a routing capacity for 4,096 paths. In addition, it also allows single input signals to be routed to multiple outputs. Data is forwarded to many outputs from one input.
The routing options of cascaded NEXUS STAR Base Devices depend on the system configuration: The number of audio channels transmitted between Base Devices relies on the number of RFOC fiber-optic interface boards reserved for this transmission.

Audio-data resolution is consistently 30 bits on the NEXUS STAR and the NEXUS system. The matrix routes all data fully transparently with regard to their standards — the data is neither evaluated nor modified.
The matrix operates in full sync with the wordclock and has a locking latency of just 3 samples.

Both mono channels and grouped signals can be routed.