Service manual

Ultraview 1030/1050 Monitors — Service Manual
3-8
SDLC Interface
The SDLC bus is the communications interface to Spacelabs Medical modules, which supply
patient data to the system. This interface is routed and connected in several ways in the monitor. It
is routed internally through the ICB PCBA to the internal plug-in module slot in the monitor. It is
also routed through the ICB and I/O Bay PCBAs for communication with the optional Capnography
pack and to an optional external module housing via the SDLC connector.
The SDLC interface runs at a 1.892352 MHz frequency. This is divided down to generate a 448 Hz
sampling rate. The SDLC communication task has a built-in program, which retrieves the data
from the bus, assembles it into a packet format, and provides it to the CPU.
The SDLC clock signals are output by the SDLC interface and are used to drive the external SDLC
bus and modules. The SDLC data signals are bi-directional and can be used both to transmit and
receive data from the intelligent modules.
Touchscreen Circuitry
The touchscreen circuitry is composed of a micro controller with internal memory and an internal
analog-to-digital converter, a separate digital-to-analog converter, and some discrete components.
Via the D/A and other signals, the micro controller drives the IR emitters on the touchscreen
PCBA. Using its internal A/D, it scans the detectors on the touchscreen PCBA looking for beam
breaks. When it detects a break, it sends a message via a serial data bus to the MPC860 CPU,
informing it of which beams are broken. The MPC860 CPU translates this into screen coordinates
and responds to key presses appropriately.
The touchscreen controller can run a calibration of the touchscreen. It drives an emitter and
monitors the detector, noting how strongly the detector responds. It repeats this for each emitter-
detector pair and maintains a table of the characteristics of each pair. It uses this data during
normal operation to drive each pair. Calibration enables it to compensate for differences in device
characteristics, device alignment, bezel transparency, and ambient lighting.
Nurse Alarm Output
When an alarm sounds, a relay on the PCBA is activated. This is connected to the nurse alarm
connector . When this connector is connected to an external nurse alarm light/buzzer, the
light/buzzer will activate when an alarm occurs.
Note:
If TONE RESET is activated, the external alarm will continue. If ALARM SUSPEND is
activated, the external alarm ends.
Clock Distribution
The clock distribution system is designed to provide low skew clocks to the core hardware
operating off of the MPC860 and PCI busses. Additional lower tolerance clocks are needed in
other peripheral areas.
A Motorola PLL-based clock driver chip is used to provide a low skew clock distribution system
and provide several optional operational configurations. This provides clocks to all of the PCI
devices with under 1.0 ns of skew, including wiring delay variation. The MPC860 and FPGA clock
skew falls within this specification also. The device can be pin-strapped programmed for various
clock frequencies including 25, 33, and/or 50 MHz. Currently both the 860 and PCI devices run at
25 MHz.