Welch Allyn Duet CO2 Module - User Manual User Manual
Page 41
Duet CO
2
Module OEM Implementation Manual
Welch Allyn OEM Technologies
Confidential
Page 41
Module Resets
External Rests (Initiated by the Host System)
• Software Reset is asserted by the host using the
the module starts in the sidestream fault mode. This is recommended as the host can be
alerted that a reset has occurred. The module can respond to host communication 2 seconds
after a reset. All configurable options will reset to default conditions.
• Reset is caused when the receive data line is held in a break condition for 10msec to
500msec. After a reset, the module starts in the sidestream fault mode. This is recommended
because the host can be aware that a reset has occurred. The module can respond to host
communication 2 seconds after a reset.. All configurable options will reset to default
conditions.
• Hard reset is caused when the receive data line is held in a break condition for more than 500
msec. This forces the microprocessor into the boot mode when the condition is released. The
boot mode is used to install new software into the flash device.
Internal Resets (Initiated internally by the Duet Module)
• Watchdog reset is caused by a watchdog timeout. After a watchdog reset, the module
responds to a Request Status command (
mode, watchdog timeout). The host must issue a reset to recover from a watchdog reset.
• Self reset is caused by a condition other than a watchdog timeout. After self reset, the module
responds to a Request Status command with the status response
OK). The host must issue a reset to recover from a self reset.
Module Time-outs
• Sensor Warm-up. During the mainstream sensor warm-up period, the host can request status
and temperature. The Duet module will indicate a FAULT=72 if the warm up rate does not
exceed the minimum rate defined in the system memory map
• Command Response Time-out - The module will send a response to all host's commands
within 1 second. Consequently, the host should have a response time-out set to 1 second.
The typical time for the module to respond to a command from the host is 50 msec.
SYSTEM BEHAVIORS - Dynamic Communications
Status Requests
The host must poll the module periodically to determine status. By sending status requests, the host
can report any problems seen by the module. When the system is in a fault status, it reports the error
that caused the fault.
WARNING
The host should NOT assume that if waveform data is being sent by the module, the
module is not reporting any errors. It is possible to report a non-fatal error condition
(e.g., Low Signal - Advisory) even when waveform data is being sent.
CO
2
Waveform Data
During Measurement and Autorun modes, the module sends a CO
2
waveform packet every revolution
(or every n
th
revolution if the Nxx command was used) of the chopper motor (approximately every 30
msec). Also, the module is responding to the host's periodic requests for status data. If waveform data
ever stops being sent, the status response will inform the host of a fault condition. The fault condition