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1.0 INTRODUCTION
1.1 Product Overview
The Honeywell Precision Barometer* (HPB) provides high accuracy absolute pressure readings in digital form. The
first-time user will be able to use the HPB within minutes, yet capability exists to configure the HPB for optimum
performance in specific applications.
The heart of the HPB measuring system is a silicon piezoresistive sensor, which contains both pressure and
temperature-sensitive elements. Digital signals representing temperature and pressure are processed by a
microprocessor to produce fully temperature compensated and calibrated pressure readings over the entire -40 to
85°C temperature range.
The HPB receives commands and sends data in either a ring or a multidrop TTL-Level configuration. Using an RS232-
to-TTL converter, up to 89 units can be connected in a ring or multi-drop configuration to a single serial port of a
computer. Group (multicast) addressing allows up to nine groups of HPBs to be addressed with a single
command. Global (broadcast) addressing will send a command to all HPBs on the bus.
Any computer having a serial port, terminal emulation software and a RS232-to-TTL converter can be connected to
the HPB to allow the user to select baud rates, sample rates, readout resolution, units of pressure and other choices.
User selected functions are set through the digital interface. The selected functions may either be used temporarily,
until the HPB is powered down, or may be stored in the internal EEPROM to automatically configure the HPB each
time power is applied.
The HPB is a low power device. It can be configured to enter a micropower shut down mode with a simple command
or by switching the state of power control line, see the OP command in section 5.10 for details. For buoy
applications, the HPB has a wave filtering routine to make data acquisition easier. See the DO command in section
5.10 for details.
1.2 Hardware Description
See Sections 8 and 9.
* For simplicity, references thoughout this manual to both HPB & HPA have been shortened to HPB.