1258 User Manual
Functional Description 3-2
Racal Instruments
©
2005
Front Panel User
Interface
The front panel includes a 16 key alphanumeric keypad and color
display for manual operator control. The internal processor uses
the soft smart keys A through D to allow control and status of the
instrument. The DEL key is used during manual input to erase,
backspace, or delete an input. The ENTER key is used to
complete a manual input. The keypad interfaces to the internal
processor through a keypad encoder via a serial interface.
Figure 3-2. Front Panel
Switching System
Controller
This switching system controller executes the system software that
controls the switching matrix, interfaces with the front panel display
and keyboard, and provides communication control and command
parsing for the remote control interfaces. On-board non-volatile
memory saves configuration information while power is off. The
controller interfaces to a display adapter module and to the
alphanumeric keypad through an on-board serial interface. The
switching cards are controlled internally using a digital I/O.
Communication
Interfaces
The GPIB, Ethernet, and RS-232 interfaces allow remote control of
the switching matrix. The RS-232 uses a serial interface provided
on the PC104 CPU module.
Switching Cards
The 1258 is comprised of one to four modular switching cards.
Each card includes a complete 64 input by 16 output switching
matrix comprised of four Analog Devices AD8116 16x16 buffered
video crosspoint switches and control logic. The switching matrix is
field expandable in 16 output increments. The entire 64x64
switching matrix is a non-blocking (full fan-out) design allowing any
input to be connected to any output or multiple outputs
simultaneously without additional input loading.
Note, however,
that the operating system software has an operational mode that
can assure that any given switch input is connected to at most one
output (MultiConnect disabled). With MultiConnect enabled
(default), a single input can be connected to multiple outputs.
The
matrix design inherently does not allow multiple inputs to be
connected to the same output.
