Honeywell PPT2 User manual

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Honeywell Precision Pressure Transducer 2
PPT2 User’s Manual

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ADS-14221 Rev. 10/16
For more information, visit us online at www.pressuresensing.com
Customer Service Email: [email protected]
No part of this manual may be reproduced or transmitted in any form or by any means, electronic or mechanical,
including photocopying and recording, for any purpose, without the express written permission of Honeywell, Inc.
Honeywell reserves the right to make changes to any products or technology herein to improve reliability,
function or design. Honeywell does not assume any liability arising out of the application or use of any product
or circuit described herein; neither does it convey any license under its patent rights nor the rights of others.

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Table of Contents
Table of Contents ................................................................................................. 3
1.0 Product Overview.......................................................................................... 4
2.0 Getting Started.............................................................................................. 5
3.0 PPT2 Command Summary ........................................................................... 9
4.0 Terminology ................................................................................................ 17
5.0 Command Descriptions (alphabetical order)............................................... 21
6.0 Electrical Connections ................................................................................ 75
7.0 Installation Recommendations, Cautions and Materials of Construction .... 77
8.0 Firmware Errata .......................................................................................... 79
Appendix A: PPT2 Binary Command Format for P3 and P4 Commands:.......... 80
Appendix B: ASCII Table .................................................................................... 83
Appendix C: Setting an Analog Pressure Set Point............................................ 84
Appendix D: RAM Initialization ........................................................................... 85

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1.0 Product Overview
The Honeywell Model PPT2 Precision Pressure Transducers provide high accuracy pressure readings in both
digital and analog form. The first-time user will be able to use the PPT2 within minutes, yet capability exists to
configure the PPT2 to optimize performance in the User’s specific applications. Throughout this User’s Manual,
the PPT2 may be referred to as Precision Pressure Transducer.
The heart of the PPT2 measuring system is a silicon piezoresistive sensor which contains both pressure and
temperature-sensitive elements. Digital signals representing temperature and pressure are processed by the
PPT2 microprocessor to produce calibrated, temperature-compensated pressure readings over the entire
operating temperature and pressure range.
Both the analog and digital outputs are internally corrected over the full operating range. The PPT2 has a digital
accuracy of 0.075% of full scale (FS). Note that full scale for a 20 psig and a 20 psia is 20 psi, but for a 20 psid it
is 40 psi, the sum of + Full scale and – Full Scale. This is important to note when determining the accuracy
allowance.
The PPT2 receives commands and sends digital data using either an RS-232 serial port or a multi-drop RS-485
serial port of a computer. (Note: many newer computers will have only USB ports, no RS-232 or RS-485 ports. A
USB converter can be used to provide the required RS-232 or RS-485 port.)
Using the RS-232 type PPT2, up to 89 units can be connected in a ring configuration to a single serial port of a
computer. The RS-485 type PPT2 allows up to 89 PPT2’s to be connected to a two-wire multi-drop bus. Group
(multicast) addressing allows up to nine groups of PPT2’s to be addressed with a single command. Global
(broadcast) addressing will send a command to all PPT2’s on the serial bus.
Any computer having a serial port and terminal emulation software can be connected to the PPT2 to allow the
user to set baud rates, reading rates, reading resolution, units of pressure and other choices. (User modified
functions must be set through the digital interface, using a computer with a serial port). The user-modified
functions may either be used temporarily, until the PPT2 is powered down, or may be stored in the PPT2 internal
EEPROM to automatically configure the PPT2 each time power is applied.
Analog output from the PPT2 16-bit digital-to-analog converter may be obtained without a host computer.

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2.0 Getting Started
2.1 OVERVIEW
The first-time user should approach the PPT2 in a manner analogous to using a word processor program; i.e.,
many features are available but one may begin by using only those of interest at the moment.
As shipped from the factory, the default settings provide a pressure transducer that will be usable for many
applications. Once the user is familiar with the performance and command structure, changes may be made and
stored using the ‘Store Parameters’ (SP) command. Once stored, the user-defined settings are activated each
time the PPT2 is powered up. This tailors the performance of the PPT2 to meet the needs of a particular
application.
2.2 EQUIPMENT NEEDED
To prepare the PPT2 for operation, three items are needed:
• A mating connector with proper wiring connections (see connector part number and wiring diagrams in
Section 6);
• A DC power supply;
• A source of pressure that is properly matched to the range and type of the PPT.
To operate the PPT2 in the analog output mode, one additional item is needed:
• Voltage Output - A five digit voltmeter with 0-5 volt range connected between Analog Out and Signal
Common. A computer is not required to read the Analog output.
To operate the PPT2 in the digital output mode, one additional item is needed:
• A computer, or host processor, having an RS-232 or RS-485 serial port (or suitable USB adapter) and
terminal emulation program.
The wiring diagram designates which PPT2 pins must connect to the computer “send”, “receive” and
“common” pins for proper communications.
2.3 TERMINAL PROGRAM SETTINGS
Enter the following settings in the terminal program:
Baud Rate: 9600
Start Bits: 1
Data Bits: 8
Stop Bits: 1
Parity: None
Attach a line feed to the carriage return.
Turn the local echo ON.
When shipped from the factory, the PPT2 is set to a baud rate of 9600, 1 start bit, 8 data bits with no parity and 1
stop bit. If the baud rate has been subsequently changed, and is unknown, it will be necessary to search all baud
rate values to reestablish communication. See the BP command description in Section 5 of this manual for
possible settings.

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2.4 INITIAL TURN-ON RESPONSE
Analog Output
The factory default analog output will provide a voltage (range 0-5V) which, when ambient pressure is applied to
the PPT2,reads:
Pressure Type
Voltage Output
(@ zero applied pressure)
Gauge units 0 volt
Differential units 2.5 volts
Absolute units A voltage representing atmospheric pressure
Digital Output
Once the wiring connections and terminal program settings are complete, the PPT2 will automatically send the
following response (or similar to) when power is applied. This reply will be generated any time power to the PPT2
is cycled off and on.
Typical Reply:
?00PPT2___10__psid
The “?00” indicates a default address device called a “null address”. This PPT2 has not yet been assigned an ID
number by the user, so it assumes the null address. The “PPT2___10__psid ” indicates a 10 psi differential
device.
2.5 COMMAND FORMAT
Any command interaction with the PPT2 requires electrical connection to the RS-232 or RS-485 serial
communications pins. There are two basic types of commands – action directing commands and information
requesting commands. These are described in Commands – Section 5.
Typical PPT2 commands have the form *ddcc = nnn <cr>
Where:
* is the command header character
dd is the integer address of the PPT (00 – 89)
cc is a command (refer to Commands – Section 5 for a complete description of commands)
= equal sign (required in some commands)
nnn additional characters (required in some commands)
<cr> carriage return is required to end all commands (do not type “<cr>”, press the ENTER/RETURN key)

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2.6 STEP-BY-STEP EXAMPLES (For a single PPT2 connection, default 00 address)
READ A SINGLE PRESSURE
Once the PPT2 is powered up and connected to a computer, enter the following command: (do not type “<cr>”,
press the ENTER/RETURN key)
User Types on the keyboard:
*00P1 <cr>
PPT2 Response:
?00CP=14.4582
Where
* indicates the start of a command
00 is the null address of the PPT2 (see note below)
P1 is the command to read the most current pressure
Note: The “?” indicates the response from a null addressed PPT2– one which has not been assigned a device ID.
A null address, 00, is coded into each PPT2 at the factory. Refer to the ID command in Section 5 for a description
of addresses and responses.
The “CP=14.4582” indicates a compensated pressure of 14.4582 psi. (Your unit may not show this specific
reading, depending on the applied pressure it is measuring.)
SET DEVICE ID
To give the PPT2 an assigned address of 01 up to 89, enter the following commands:
*00WE<cr> This enables the PPT2 to change a parameter in RAM
*00ID=01<cr> This sets the null addressed PPT2 to device ID=01.
Note: The new device ID is now used in subsequent commands
*01S=<cr>
Response: #01S=00052036 (serial number)
The “#” now replaces the “?” in the header and indicates the PPT2 response is from an address-
assigned unit.
READ PRODUCTION DATE
To read the production date, enter the following command:
*01P=<cr>
Response: #01P=04/13/11

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READ CONTINUOUS PRESSURE
For continuous pressure readings (factory default rate = 5 per second) enter the following command:
*01P2<cr> This enables a continuous stream of compensated pressure readings to flow into the
terminal program.
$*99IN<cr> This is the best way to stop the continuous pressure reading commands. The ‘$’
character temporarily stops, or suspends, the digital output of the PPT2. The *99IN
command stops the continuous pressure or temperature readings.
CHANGE TO A NEW READING RATE
Enter the following command:
*01WE <cr> This enables the PPT2 RAM to accept a changed parameter.
*01I=M200<cr> This sets the integration time to value M200, which corresponds to an output reading
every 2 seconds.
The reading rate will change to one every 2 seconds. I= is an abbreviation for Integration time, which determines
how long to accumulate corrected pressure values between readings. Each integration period gathers the data for
one pressure reading output (see Section 4.2 What is integration?). The range of integration times can be set by
specifying readings per second (I=R50 for 50 readings/sec) or in 10 millisecond intervals (I=M600 for 6 seconds).
The factory-set integration time is 200 milliseconds or 5 readings per second (I=M20).
The output data rate can also be altered by use of the idle count (IC) command or by changing the operating
mode (OP) command. See Section 5 for description of these commands.
REPEAT THE READ CONTINUOUS PRESSURE STEP ABOVE
Notice the slower output rate of one reading every 2 seconds.
TRY OTHER COMMANDS
Experiment with other commands to become familiar with the command structures. A short overview of each
command with input and response examples is shown in Section 3 Command Summary. See Section 5—
Commands for complete command descriptions. Until an SP=ALL command is executed, no changes will be
stored in the PPT2 EEPROM. Re-apply the power or send an IN=RESET command to revert to the settings last
saved in EEPROM.

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3.0 PPT2 Command Summary
The PPT2 command set is summarized in Table 1.0 – Command List. A more detailed description of each
command can be found in the subsequent command descriptions in Section 5.
Table heading explanations for Table 1.0 – Command List:
Command Code: Two-character code (cc) in the command format (see Section 2.5). The
command code characters may be one letter followed by an ‘=’ equal
sign, two letters, or a letter and a number. The letters are not case
sensitive; i.e. either upper case or lower case may be used. (The PPT2
internally converts all lower case characters to upper case.)
Action Directing Command: Does this command change the PPT2 configuration?
Yes – The command changes the PPT2 configuration as an action
directing command.
No – The command is only an Information Request Command.
Information Request Command: The command initiates a response (output) from the PPT2, with the
output content being specific to that particular PPT2.
Sequential Response with Group or Global Address:
Commands that begin with a group or global address (ID=90-99), are
passed through the PPT2 ring configuration network from one device to
the next and eventually end up back at the host computer. The PPT2
response is sent with the command through the network.
Before – The PPT2 response is sent before the group or global
command is repeated.
After – The PPT2 response is sent after the group or global command is
repeated.
No – The PPT2 just passes the command through the network with no
response.
Input or Output: Is information input to the PPT2 or output from the PPT2?
In – Command is only used to input (action direct command) to the
PPT2.
Out – Command is only used to request output (Information Request
Command ) from the PPT2.
Both – Command can be used for either IN or OUT purposes.
Requires Write Enable: Is a WE command required before for this command?
Yes – When sent as an action directed command, it must be preceded
by a WE command.
No – Never requires a WE command beforehand. These are Information
Request Commands.
Terminates Continuous Commands:
Will this command stop the PPT2 digital output flow?
Yes – This command will end the continuous flow of the P2, P4, or T2
replies.
No – Command will not stop the continuous digital output flow.