Setra 470 Operating Manual
Model 470
Digital Pressure Transducers
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Contents
SECTION ONE: Introduction ..................................................................................................... 3
1.1 About the Setra 470 ............................................................................................................ 3
1.2 About this Manual................................................................................................................ 4
SECTION TWO: Installing the Model 470 ................................................................................. 5
2.1 Power Connections ............................................................................................................. 5
2.2 Pressure Connections .........................................................................................................5
2.3 Communications Hardware ................................................................................................. 5
SECTION THREE: Communications Interfacing ..................................................................... 7
3.1 Communications Software Protocols .................................................................................. 7
3.2 Executing a Function........................................................................................................... 7
3.3 Clearing a Number or Function ........................................................................................... 7
3.4 Functions ............................................................................................................................. 8
3.5 In Case of Error Messages.................................................................................................11
3.6 Symbols............................................................................................................................. 12
SECTION FOUR: Precision Measurement Functions ........................................................... 13
4.1 Interrogation ...................................................................................................................... 13
4.2 Converting Engineering Units............................................................................................ 13
4.3 User Defined Engineering Units in Nonvolatile Memory ................................................... 14
4.4 User Defined Engineering Units in Volatile Memory.......................................................... 15
4.5 Tracking Min and Max Values ........................................................................................... 16
4.6 Setting and Checking Alarm Setpoints in Nonvolatile Memory ......................................... 16
4.7 Setting and Checking Alarm Setpoints in Volatile Memory................................................ 17
4.8 Using the Tare and Zero Function ..................................................................................... 17
4.9 Repetitive Reporting.......................................................................................................... 18
4.10 Reporting Setup Summary ................................................................................................ 18
4.11 Digital Altimeter Setting Indicator (DASI)........................................................................... 19
SECTION FIVE: Setup Functions ............................................................................................ 21
5.1 Status After Power is Applied ............................................................................................ 21
5.2 Changing the Baud Rate ................................................................................................... 21
5.3 Disabling Engineering Units in Nonvolatile Memory.......................................................... 22
5.4 Disabling Engineering Units in Volatile Memory................................................................ 23
5.5 Self Diagnostics................................................................................................................. 24
5.6 Software Revision Number................................................................................................ 25
5.7 Verify Function................................................................................................................... 25
5.8 Stability Indicator ............................................................................................................... 25
SECTION SIX: Altitude Measurement Functions................................................................... 27
6.1 Standard Altitude Measurement ........................................................................................ 27
6.2 True Corrected Altitude Measurement .............................................................................. 27
6.3 Relative Altitude Measurement.......................................................................................... 29
SECTION SEVEN: Calibration ................................................................................................. 30
7.1 Calibration ......................................................................................................................... 30
7.2 Calibration and Program Enable ....................................................................................... 30
7.3 Zero Calibration................................................................................................................. 31
7.4 Span Calibration................................................................................................................ 32
Appendix I ................................................................................................................................. 33
Interface Program Example............................................................................................... 33
Specifications .................................................................................................................... 34
Limited Warranty ...................................................................................................................... 35
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1.1 About the Setra 470
The Setra 470 Digital Pressure Transducer is a highly accurate pressure measurement
system utilizing the patented SETRACERAM sensor, advanced micro-computer based
electronics, and sophisticated firmware, resulting in a 0.02% F.S. system accuracy
traceable to the National Institute of Standards and Technology.
The Setra 470 accurately measures and reports barometric pressure. It also processes
the pressure data to provide useful information in a number of applications; barometric
altimetry, digital altimeter setting indication, and laboratory calibration.
The digital design of the Setra 470 provides a simple and reliable communications
interface for easy integration into digital control systems. This, in addition to the digital
signal processing of the sensing element signal, allows system designers to eliminate the
inaccuracies and cost of an analog data acquisition module.
SETRA
Model 470
Digital Pressure Transducer
SECTION ONE
Introduction
The patented sensor and signal processing, the ease of operation, and the rugged design
of this unit will provide years of reliable and accurate service.
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1.2 About this Manual
This manual contains information you need to use the Setra 470. Whenever possible, the
information is presented in nontechnical language so that you can install and use the
transducer without any specialized training.
However, the Setra 470 can be used in a wide variety of data acquisition systems, laboratories,
calibration labs, and digital weather systems. In order to use the Setra 470, you must understand
general concepts of interfacing digital equipment, to know how to make your equipment communicate with the Setra 470 according to the general explanations in this manual, and know how to
use or manipulate the data in your computer system.
The chapters in the manual are organized to lead you through all the steps required to connect
and use a Setra 470. It is unlikely that you will use all of the functions of the Setra 470 in any
single application, so select the parts of the manual you need for your application from the
following list.
Pressure and electrical connections Section Two
General interface requirements Section Three
Pressure measurement functions Section Four
Setup functions Section Five
Altitude measurement functions Section Six
Calibration functions Section Seven
Though the Setra 470 is easy to operate, read this manual carefully before use. It helps you take
full advantage of the functions and performance of the transducer, particularly in cases where
several functions interact and are used together.
Volatile memory and Nonvolatile memory as described in this manual are defined as follows:
Volatile memory - Information that is temporary and is gone if you switch the power off.
Nonvolatile memory - Information that is permanent, it doesn’t disappear when you
switch the power off.
Typographical conventions used in this manual include the following:
1. BOLD characters indicate information you send to the 470.
2. “Quotation marks” enclose messages you receive from the 470.
3. CAPITAL LETTERS indicate the names of functions of the 470.
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2.1 Power Connections
The Setra 470 requires a 5 volt DC power supply regulated to ±1% which can supply 90 milliamps
of current. Use of a correctly rated and regulated power supply is important for correct operation
of the digital electronics in the Setra 470.
To apply power to the Setra 470, follow these steps:
1. Connect a DB9P (D-Subminiature 9 pin male connector) to a cable from the
5 VDC power supply with the following pinout:
Pin 3 is connected to power supply ground.
Pin 9 is connected to +5 VDC.
All other pins are not connected.
2. Locate the DB9S power connector on the Setra 470. It is a 9 pin D-Subminiature female
connector to the right of the pressure port and is marked “Power” on the label.
3. Insert the male connector on the power supply cable into the female connector on the
Setra 470 and secure it by tightening the mounting screws on the male connector into the
flanges on the female connector.
SECTION TWO
Installing the Model 470
4. In some installations there is a requirement for the case of the transducer to be grounded
to or through a shield. The Setra 470 case is connected internally to power supply ground
and therefore must not be connected to any other ground.
5. Turn on the power supply.
2.2 Pressure Connections
The pressure connection on the Setra 470 is a standard 1/8” diameter barbed hose fitting, 1/2” in
length. You can remove this fitting and install a different fitting in the
10-32 threaded female port.
The Setra 470 transducer is designed to measure the pressure of clean, dry, nonconducting,
noncorrosive gases only.
The Proof Pressure of the Setra 470 (the maximum pressure which can be applied without
disturbing the calibration of the transducer) is 150% of the full scale pressure. To ensure that the
pressure applied to the transducer does not exceed the proof pressure, install properly rated relief
valves in any system this unit is connected to.
2.3 Communications Hardware
The Setra 470 is equipped with a standard bidirectional RS-232 communications port. The RS232 Communications Standard describes in detail the requirements and conventions of RS-232.
The Setra 470 implements a very simple subset of the standard, and does not provide handshaking lines (such as DSR, CTS, or DTR).
The Setra 470 RS-232 serial interface is a DTE type (Data Transmission Equipment). This
means that it receives data on pin 3 and transmits data on pin 2. This is in contrast to DCE (Data
Communication Equipment) which receives data on pin 2 and sends data on pin 3. Because the
RS-232 Standard describes communications between DTE and DCE devices, the host device
you connect to the Setra 470 (computer terminal, or data acquisition system) must have a pinout
which correctly corresponds to the Setra 470 pinout.
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If it does not, (i.e. if the computer also has a DTE interface, and therefore transmits on its own pin
2, and receives on its own pin 3), a “reversing” or “null modem” cable is required for connection.
This is simply a cable which connects pin 2 and 3 of the Setra 470 to pins 3 and 2 of the computer respectively. This kind of cable is commercially available and is also available from Setra.
In addition, some computers which do require handshaking lines will require a connection between the two pins on the computers connector named DTR and DSR (Data Terminal Reading
and Data Set Ready) in order to enable it to communicate with the 470.
To connect to the Setra 470 RS-232 port:
1. Connect a DB9S (D-Subminiature 9 pin female connector) to a cable from the host with
the following pinout:
6 7 8 9 Pin Description
• • • • 2 TXD - transducer transmits data
• • • • • 3 RXD - transducer receives data
1 2 3 4 5 5 GRD - signal ground
2. Connect the shield of the cable from the host to the threaded standoffs on each side of
the connector shell. Do not use a cable longer than 15 meters.
3. Locate the DB9P communications connector on the Setra 470. It is a
D-Subminiature 9 pin male connector to the left of the pressure port and is marked “Commu-
nications” on the label.
4. Insert the female connector on the host communications cable into the male connector on
the Setra 470 and secure it by tightening the mounting screws on the female connector into
the flanges on the male connector.
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3.1 Communications Software Protocols
The Setra 470 RS-232 communication port allows several rates of data transfer (baud rates)
between the Setra 470 and the host device. Both devices must communicate at the same data
rate.
The factory default baud rate of the Setra 470 is 2400. Therefore, the device connected to the
Setra 470 initially must also be set to 2400. To change the Setra 470 baud rate refer to Section
5.2.
The Setra 470 transmits data as a series of standard ASCII characters, formulated by carriage
return and line feed characters. No software or hardware handshaking or error checking protocols are used. Each character of data is represented in a specific format:
1 start bit
8 data bits
1 stop bit
no parity
Most computers, terminals and data acquisition systems used as hosts for the
Setra 470 allow adjustment of the format used to represent the characters of data. Adjust the
format of the host to match that of the Setra 470 in order to allow the devices to communicate.
SECTION THREE
Communications Interfacing
The Setra 470 ignores carriage returns, line feeds, blank spaces and all other characters which
are not command characters listed in the summary in Section 3.4.
3.2 Executing a Function
You may execute all of the functions of the Setra 470 by transmitting the appropriate command
from the host to the transducer through the RS-232 interface. The commands are standard
alphabetic characters that correspond to the functions described in this manual, and are transmitted in ASCII code.
Read the detailed explanations of the functions you want to execute in the following sections of
the manual before beginning.
The table in Section 3.4, summarizes the functions and characters which the 470 recognizes, and
the character commands for each. For the convenience of some software programmers, the
decimal and hexadecimal ASCII values of the command characters are also listed.
To execute a function, transmit the appropriate character code from a terminal or computer. For
example, to interrogate the transducer for a pressure reading, transmit the letter P, for PRINT, to
the transducer. The transducer reports data back to the computer.
Details of this and all other functions are included in following sections of the manual.
3.3 Clearing a Number or Function
To clear a number or function that is partially or incorrectly transmitted, transmit C, for CLEAR.
This clears the previously transmitted data without affecting any other functions which may be in
use.
To reset the Setra 470 to its power up condition, transmit - C, (the minus symbol followed by C).
This clears the ZERO/tare value, shuts off MIN/MAX and CONVERTs back to the original engineering units of pressure. All of these functions are described in later sections of this guide.
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3.4 Functions
This summary of functions is provided for reference only. See the following sections for details on
how to use each function. Command codes must be in capital letters.
Function Command ASCII Hex
Name Code Code Code Description Section
PRINT P 80 $50 Report information 4.1
CONVERT U 85 $55 CONVERT engineering 4.2
ZERO Z 90 $5A Perform relative or 4.8
CLEAR C 67 $43 CLEAR the number or 3.3
SEA LEVEL B 66 $42 True pressure to SEA 4.11
ASCII
to a computer or data
acquisition system.
units being reported.
absolute tare value.
key sequence being
transmitted.
LEVEL or vice versa.
VERIFY V 86 $56 Test communications 5.7
and report pressure
measurement range.
SETUP S 83 $53 Terminate the number
or key sequence being
transmitted.
SETUP SP 83 80 $53 $50 Report SETUP summary 4.10
PRINT to host, including elevation
and min/max values.
SETUP SA 83 65 $53 $41 Change Hi and Lo ALARM 4.6
SETPOINTS setpoints in nonvolatile
memory.
SETUP SM 83 77 $53 $4D Enter MIN/MAX tracking 4.5
MIN/MAX mode.
SETUP ZERO SZ 83 90 $53 $5A Perform ZERO calibration 7.3
procedure.
SETUP SPAN SF 83 70 $53 $46 Perform SPAN calibration 7.4
procedure.
SETUP SB 83 66 $53 $42 Enter station elevation for 4.11
SEA LEVEL SEA LEVEL correction.
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— — 45 $2D Shuts off the
function whose
command code follows it.
— CLEAR —C 45 67 $2D $43 Turn off MIN/MAX, clear 3.3
the tare value, convert to the
original engineering units.
—MIN/MAX —M 45 77 $2D $4D Exit MIN/MAX tracking mode. 4.5
—CONV —U 45 85 $2D $55 Reverts to reporting data in 4.2
the factory default pressure
units.
—ZERO —Z 45 90 $2D $5A Clear any values being 4.8
Zero/Tare’d from the
reported reading.
—PRINT —P 45 80 $2D $50 Turn off repetitive print mode. 4.9
BAUD RATE —5555S * * Change the baud rate. 5.2
DISABLE UNITS —2222S * * Disable engineering units 5.3
in nonvolatile memory.
REVISION —7777S * * Display revision level of 5.6
NUMBER firmware.
SELF- —8888S * * Execute internal diagnostics 5.5
DIAGNOSTICS routine.
STABILITY —1111S * * Change parameter for 5.8
display at stable pressure
indicator.
RAM SETUP RSA * * Change Hi and Lo ALARM 4.7
SETPOINTS setpoints in volatile memory.
RAM DISABLE R-2222S * * Disable engineering units 5.4
UNITS in volatile memory.
RAM USER RxUx * * Enter conversion ratio for 4.4
DEFINED UNITS non-standard engineering
units in volatile memory.
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ASCII
Function Command ASCII Hex
Name Code Code Code Description Section
USER xUx * * Enter conversion ratio for 4.3
DEFINED non-standard engineering
UNITS units in nonvolatile memory.
0 0 48 $30 The number 0.
1 1 49 $31 The number 1.
2 2 50 $32 The number 2.
3 3 51 $33 The number 3.
4 4 52 $34 The number 4.
5 5 53 $35 The number 5.
6 6 54 $36 The number 6.
7 7 55 $37 The number 7.
8 8 56 $38 The number 8.
9 9 57 $39 The number 9.
* See ASCII codes for individual characters.
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3.5 In Case of Error Messages
The following summary explains the meaning of error messages that you may receive from the
470 in response to a command, and also tells you what actions to take in response to the error
message.
Message Explanation What to Do
1. “UNABLE” The transducer cannot accept or Transmit C, to CLEAR the
execute a number or function previously transmitted data.
command it received, or you To execute setup or pressure
have attempted to execute measurement functions, first
a setup function or a pressure use the CONVERT function
measurement function while the so that the transducer is
transducer is reporting data in reporting data in units of
units of altitude. pressure.
2. “OFLO” The output data is over-ranged Convert to different pressure
or the user-conversion exceeds units.
the number of digits available.
3. “BUSY” The transducer is acquiring a Wait for the transducer to
stable reading, or is executing respond or transmit C, for
a function. CLEAR to stop the function
being executed.
4. “ERR” The sensor is damaged or not Contact Setra immediately
working properly for help in diagnosing the
problem, and for repair if
necessary.
5. “PROTEC” The program enable switch Set the program enable
(Section 7.2) is “ON” and must switch to “OFF”, transmit C,
be set to “OFF”. for CLEAR, to resume normal
operation.
6. “NO CAL” The program enable switch Set the program enable switch
(Section 7.2) is “OFF”, and to “ON” and transmit S, for
must be set to “ON” before SETUP to continue executing
the 470 can execute the the function, or don’t set the
previous command. program enable switch to “ON”
and transmit C, to resume
normal operation.
7. “D-NOS” The 470 has entered a self Transmit S, as in step 4 of
diagnostic routine (Section 5.5). Section 5.5 to allow the 470
to complete executing the
diagnostic described in that
section.
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