Service manual

Theory
3-13
• The GDS is the patient database containing parameter data from the modules, including current,
general, trend, and waveform data.
• The Remote Interface System handles Ethernet connections to remote monitors and modules. It
broadcasts the existence and configuration of the network devices to each other. It enables the
user to view remote parameters and to remotely press keys across the network. The Remote
Interface System downloads the module table code to remote monitors to create the same human
interface on multiple monitors. In addition, it supports the alarm watch and remote view functions
and handles multicasted waveform data.
• The Recorder subsystem controls local recorders and network recorders.
• The Alarm subsystem handles alarms notification. Modules send alarm conditions over SLDC,
and in response, the alarm subsystem sends alarm messages to the tone, display, record, and
network tasks. The module receives messages from the network for alarm watch alarms and from
SDLC tasks for local module alarms.
Minor System Tasks and Device Drivers:
• The main subsystems communicate display information to the Display Manager (DM) task. The
DM receives display changes from these subsystems and issues the appropriate graphics
primitives to update the display through the video device driver.
• The subsystems interface to SDLC via Rx/Tx buffers in memory, driven by a 32-Hz interrupt.
• The Ethernet interface uses dynamic memory for receive and transmit. One Ethernet interrupt
occurs for both receive packets and command completes. An Ethernet write command is used for
transmitting packets. An “Ethernet-user” task maintains and uses a routing lookup table to switch
network packets to the appropriate network driver — the Ethernet device driver or the wireless
network card device driver.
• The Recorder subsystem uses these SDLC/Ethernet drivers directly.
• The touchscreen driver and the external keyboard and mouse drivers provide x-y coordinates to
the keyboard task for activating the on-screen keys.
• The Tone task is responsible for timing and prioritizing tones from the Alarm subsystem, the Keys
subsystem, and other system tasks. It receives commands to turn ON and OFF, to suspend, and
to change volume. It also looks up wavetable tones and sends them to the Mixer task.
• The Mixer task mixes the alarm sounds with information tones as needed. Both the Tone and
Mixer tasks talk to the audio hardware via the audio device driver.