Advertisement
System Description
Software
Dry Air Capillary
Software
Instrument Control
Monitoring Signals
8-4
Model 42i Trace Level Instruction Manual
The dry air capillary along with the pump is used to control flow in the dry
air line.
The processor software tasks are organized into four areas:
Instrument Control
●
Monitoring Signals
●
Measurement Calculations
●
Output Communication
●
Low-level embedded processors are used to control the various functions on
the boards, such as analog and digital I/O and heater control. These
processors are controlled over a serial interface with a single high-level
processor that also controls the front-panel user interface. The low-level
processors all run a common piece of firmware that is bundled with the
high-level firmware and loaded on power-up if a different version is
detected.
Each board has a specific address that is used to identify to the firmware
what functions are supported on that board. This address is also used for
the communications between the low-level processors and the high-level
processor.
Every tenth of a second the frequency counters, analog I/O, and digital I/O
are read and written to by the low-level processor. The counters are
accumulated over the past second and the analog inputs are averaged over
that second. The high-level processor polls the low-level processors once
per second to exchange the measurement and control data.
Signals are gathered from the low-level processors once per second, and
then processed by the high-level processor to produce the final
measurement values. The one-second accumulated counts representing the
NO/NO
are accumulated and reported for the user-specified averaging
x
time. If this averaging time is greater than ten seconds, the measurement is
reported every 10 seconds. The one-second average of the other analog
inputs are reported directly (no additional signal conditioning is performed
by the high-level processor).
In auto mode, every ten seconds the NO/ NO
processor waits three seconds for the reaction chamber to flush and
solenoid switches and the
x
Thermo Fisher Scientific
Advertisement
Troubleshooting
