GE Dash 3000 Service Manual page 52

Optional thermal printer
Optional alarm light indicator
Compact flash wireless card
Peripheral expansion interface
DAS communication
2-32
Equipment overview: Theory of operation
The thermal printer includes complete control of the print head to print
the desired waveforms and text as well as monitor power consumption.
The host processor on the main processing board has direct
communication via an 8-bit data bus to the processor residing within the
thermal recorder.
The +9-18 V power supplied to the writer is heavily filtered to provide
the storage capability to smooth power surges and transients caused by
abnormal thermal printing. Such printing may occur if the patient
monitor is subjected to ESU noise. In addition, a writer current limiting
circuit restricts the current to the writer to 2.5 A. If this current limit is
exceeded, the circuit faults and requires the current limiting circuit to
reset through a microprocessor port.
An alarm light indicating two levels of visual alarms resides in the
handle of the Dash 3000 patient monitor and in the display bezel of the
Dash 4000/5000 patient monitors. Red and yellow alarm lights
illuminate by addressing an ASIC output port. The Dash 3000 alarm
light interfaces to the processor/power management PCB via the 40-pin
writer interface. The Dash 4000/5000 alarm lights interface to the
processor/power management PCB via the 100-pin DAS/Display /
Keyboard interface.
The main processor contains a compact flash (CF) card controller, which
complies with the CF standard. One 50-pin fully compliant Type II CF
card slot is supported in this design for a wireless card.
A 20-pin peripheral expansion interface is provided to support future
use. An active low peripheral present signal may be polled by software to
identify when a peripheral is attached to the patient monitor.
Asynchronous, AUX, and a switched Ethernet serial communication
channels are supported as well as switched +9-18 V and +5 V power.
The microprocessor communicates with the DAS processor using the
second serial communication controller (SCC) of the communication
processor module (CPM). This asynchronous communication channel
operates at TTL levels and is optically isolated within the DAS.
Dash 3000/4000/5000 2000966-542D