Vaisala PTB220 User Manual
PTB220 Series Digital
Barometers
USER'S GUIDE
M210194EN-A
AUGUST 2001
_________________________________________________________________________CONTENTS
Table of contents
CHAPTER 1 GENERAL INFORMATION ............................................................. 1
Safety ..............................................................................................1
Warranty .........................................................................................2
CHAPTER 2 PRODUCT DESCRIPTION .............................................................3
Introduction ....................................................................................3
BAROCAP® pressure sensor .......................................................4
Measurement principle..................................................................6
Block diagram ................................................................................7
CHAPTER 3 GETTING STARTED ....................................................................... 9
CHAPTER 4 COMMISSIONING .........................................................................11
Operating modes .........................................................................12
SMODE Selecting the sending mode .......................................12
MMODE Selecting the measurement mode ............................. 13
PULSE Selecting the PULSE output mode ..............................14
Software settings .........................................................................16
SERI Serial bus settings ...........................................................16
ECHO Setting the serial bus echo on/off..................................17
FORM Defining the output format............................................. 17
EFORM Defining the error output format .................................22
DFORM Defining the display format.........................................22
UNIT Setting the pressure and temperature units ....................25
HHCP Setting the height of height correction...........................25
AVRG Setting the averaging time.............................................26
INTV Setting the output interval................................................27
ADDR Setting the barometer address (for POLL mode) ..........27
SCOM User specific SEND command .....................................28
PSTAB Setting the pressure stability indicator .........................29
PLARM Setting the pressure alarm levels................................30
PDMAX Setting the pressure difference limit ...........................30
KEYLOCK Setting the keyboard lock on/off .............................32
Hardware settings........................................................................33
CHAPTER 5 INSTALLATION.............................................................................37
Mounting.......................................................................................37
Electrical connections................................................................. 38
Grounding.....................................................................................40
Pressure connections .................................................................41
CHAPTER 6 OPERATING.................................................................................. 43
RUN and STOP modes ................................................................43
R Starting the continuous output ..............................................44
S Stopping the output ...............................................................44
SEND Outputting a single message only .................................45
V Verification message .............................................................45
DNOS Self-diagnostics .............................................................45
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TRACK Setting the pressure tracking mode on/off .................. 46
PLIM Pressure limit listing........................................................ 46
RESET Resetting the barometer ............................................. 47
POLL mode .................................................................................. 48
SEND Outputting one single message .................................... 48
OPEN Setting a barometer from POLL mode to STOP mode. 49
CLOSE Setting a barometer from STOP mode to POLL mode49
SEND mode.................................................................................. 50
PULSE mode................................................................................ 51
Operating the local display and keyboard................................ 51
CHAPTER 7 ADJUSTMENT AND CALIBRATION ........................................... 55
Introduction ................................................................................. 55
CORR Listing linear and multipoint corrections ....................... 57
LC Linear corrections ............................................................... 59
MPC Multipoint corrections ...................................................... 60
Offset and gain adjustment........................................................ 61
LCI Entering linear corrections................................................. 61
Multipoint adjustment................................................................. 62
MPCI Entering multipoint corrections ...................................... 62
Calibration ................................................................................... 63
CALD Storing the new date of calibration................................ 64
CHAPTER 8 SELF-TESTING AND PROBLEM HANDLING ............................ 65
Returning the serial communication parameters .................... 65
Diagnostic commands................................................................ 66
? Basic information on the barometer settings ....................... 66
VERS Software version ........................................................... 67
SNUM Serial number ............................................................... 67
ERRS Error message output .................................................. 67
TEST n Testing transducer operation ...................................... 68
C n Listing transducer coefficients........................................... 69
PTEST Testing pulse output mode .......................................... 69
CHAPTER 9 TECHNICAL SPECIFICATIONS .................................................. 71
Barometric pressure ................................................................... 71
Operating range ....................................................................... 71
Accuracy ...................................................................................... 71
General ......................................................................................... 72
Mechanics .................................................................................... 73
Electromagnetic compatibility ................................................... 73
Options......................................................................................... 74
Accessories ................................................................................. 74
APPENDIX A HARDWARE CONFIGURATIONS ............................................... 77
APPENDIX B PIN ASSIGNMENTS..................................................................... 79
APPENDIX C RS232C/TTL LEVEL SERIAL INTERFACE ................................ 81
APPENDIX D PULSE OUTPUT MODE............................................................... 83
APPENDIX E ANALOG OUTPUT ....................................................................... 87
Pin assignment............................................................................ 90
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APPENDIX F MULTIPLE PTB220 BAROMETERS ON RS232C.......................91
APPENDIX G OPTIONAL RS485/422 INTERFACE OF PTB220 BAROMETERS93
APPENDIX H SERIAL INTERFACE COMMANDS .............................................97
Commissioning commands........................................................97
Operating commands ..................................................................97
Maintenance commands .............................................................98
Diagnostic commands ................................................................98
APPENDIX I CHECKSUM ..................................................................................99
APPENDIX J PRESSURE TENDENCY ............................................................101
APPENDIX K ERROR MESSAGES...................................................................102
APPENDIX L SPECIAL EMULATION MODE...................................................103
PA11A..........................................................................................103
P Mode....................................................................................103
Automode ...............................................................................104
Setra 470 .....................................................................................105
APPENDIX M PRESSURE CONVERSION CHART ..........................................107
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CHAPTER 1_______________________________________________________ GENERAL INFORMATION
CHAPTER 1 GENERAL INFORMATION
Safety
Throughout the manual important instructions regarding the safety
considerations are focused as follows.
WARNING
CAUTION
NOTE
Warning denotes a hazard. It calls attention to a procedure, practice,
condition or the like, which, if not correctly performed or adhered to,
could result in injury to or death of personnel.
Caution denotes a hazard. It calls attention to a procedure, practice,
condition or the like, which, if not correctly performed or adhered to,
could result in damage to or destruction of part or all of the product.
Note highlights important information. It calls attention to an essential
procedure, practice, condition or the like.
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Warranty
Vaisala hereby represents and warrants all Products manufactured by Vaisala and sold hereunder to be
free from defects in workmanship or material during a period of twelve (12) months from the date of
delivery save for products for which a special warranty is given. If any Product proves however to be
defective in workmanship or material within the period herein provided Vaisala undertakes to the
exclusion of any other remedy to repair or at its own option replace the defective Product or part thereof
free of charge and otherwise on the same conditions as for the original Product or part without
extension to original warranty time. Defective parts replaced in accordance with this clause shall be
placed at the disposal of Vaisala.
Vaisala also warrants the quality of all repair and service works performed by its employees to products
sold by it. In case the repair or service works should appear inadequate or faulty and should this cause
malfunction or nonfunction of the product to which the service was performed Vaisala shall at its free
option either repair or have repaired or replace the product in question. The working hours used by
employees of Vaisala for such repair or replacement shall be free of charge to the client. This service
warranty shall be valid for a period of six (6) months from the date the service measures were
completed.
This warranty is however subject to following conditions:
a) A substantiated written claim as to any alleged defects shall have been received by Vaisala
within thirty (30) days after the defect or fault became known or occurred, and
b) the allegedly defective Product or part shall, should Vaisala so require, be sent to the works of
Vaisala or to such other place as Vaisala may indicate in writing, freight and insurance prepaid and
properly packed and labelled, unless Vaisala agrees to inspect and repair the Product or replace it on
site.
This warranty does not however apply when the defect has been caused through
a) normal wear and tear or accident;
b) misuse or other unsuitable or unauthorized use of the Product or negligence or error in storing,
maintaining or in handling the Product or any equipment thereof;
c) wrong installation or assembly or failure to service the Product or otherwise follow Vaisala's
service instructions including any repairs or installation or assembly or service made by unauthorized
personnel not approved by Vaisala or replacements with parts not manufactured or supplied by Vaisala;
d) modifications or changes of the Product as well as any adding to it without Vaisala's prior
authorization;
e) other factors depending on the Customer or a third party.
Notwithstanding the aforesaid Vaisala's liability under this clause shall not apply to any defects arising
out of materials, designs or instructions provided by the Customer.
This warranty is expressly in lieu of and excludes all other conditions, warranties and liabilities, express
or implied, whether under law, statute or otherwise, including without limitation ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR OF FITNESS FOR A PARTICULAR PURPOSE and
all other obligations and liabilities of Vaisala or its representatives with respect to any defect or
deficiency applicable to or resulting directly or indirectly from the Products supplied hereunder, which
obligations and liabilities are hereby expressly cancelled and waived. Vaisala's liability shall under no
circumstances exceed the invoice price of any Product for which a warranty claim is made, nor shall
Vaisala in any circumstances be liable for lost profits or other consequential loss whether direct or
indirect or for special damages.
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CHAPTER 2___________________________________________________ PRODUCT DESCRIPTION
CHAPTER 2 PRODUCT DESCRIPTION
Introduction
The PTB220 series barometers are fully compensated digital
barometers designed to cover a wide range of environmental pressure
and temperature. They can be used successfully both in accurate
pressure measurement applications at room temperature and in
demanding automatic weather station applications.
The PTB220 series digital barometers use the BAROCAP® silicon
capacitive absolute sensor developed by Vaisala for barometric
pressure measurement applications.
The measurement principle of the PTB220 series digital barometers is
based on an advanced RC oscillator and three reference capacitors
against which the capacitive pressure sensor and the capacitive
temperature compensation sensor are continuously measured. The
microprocessor of the barometer performs compensation for pressure
linearity and temperature dependence.
The pressure and temperature adjustment in the PTB220 consists of
seven temperature levels over the operating temperature range of the
barometer and of six to eleven pressure levels over the operating
pressure range of the barometer at each temperature level. The
calculated individual basic pressure and temperature adjustment
coefficients are stored in the EEPROM of each pressure transducer.
The user cannot change these basic factory adjustments.
The multipoint fine adjustment for pressure and the final pressure
calibration of the PTB220 Class A barometers is done using a manual
Ruska 2465 dead-weight tester. The multipoint fine adjustment and
calibration of the Class B barometers is done automatically using
electronic working standards.
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The PTB220 series digital barometers are available with one, two or
three pressure transducers. Although one pressure transducer is
usually the most appropriate configuration, some applications may
benefit from additional pressure transducers. Two or three pressure
transducers provide for a self-diagnostic feature: the user can set an
alarm limit within which the pressure transducers must agree for
reliable measurement. The PTB220 series barometers can also be
configured to measure two separate pressures.
A local LCD display on the cover is also available as a configuration
option. The display has a backlight, which makes the display easy to
read at any light conditions. The display has two rows and it can
simultaneously indicate the barometric pressure, the three-hour
pressure trend and the WMO pressure tendency code.
The user can define various specific application settings, such as serial
bus settings, averaging time, output interval, output format, display
format, error message field, pressure unit and pressure resolution. It is
also possible to select different sending modes for power-up situation
such as the free running mode, the stand-by mode and a mode with
one automatically sent message. A fast measurement mode with ten
measurements per second can also be selected. The factory settings
have been chosen so that both a fast settling time and a high resolution
are achieved. In applications where fast settling time is not required,
longer averaging times are recommended to reduce environmetal
pressure noise.
As a standard, there are RS 232C full duplex and bidirectional TTL
level serial interface in the barometer. In addition the user can select
either an RS 485/422 two-wire half duplex serial interface or a pulse
output interface with user selectable pulse rate, pressure resolution and
pressure offset.
The PTB220 series digital barometers are traceable to National
Institute of Standards and Technology (NIST) in the USA.
BAROCAP® pressure sensor
The PTB220 digital barometers use the BAROCAP® silicon
capacitive absolute pressure sensor developed by Vaisala for
barometric pressure measurement applications. The BAROCAP
sensor has excellent hysteresis and repeatability characteristics, low
temperature dependence and a very good long-term stability. The
ruggedness of the BAROCAP® sensor is outstanding and the sensor is
resistant to mechanical and thermal shocks.
®
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CHAPTER 2___________________________________________________ PRODUCT DESCRIPTION
Silicon diaphragm
Thin film metallization
FIGURE 2-1 The BAROCAP
The BAROCAP® pressure sensor consists of two layers of single
crystal silicon having a layer of glass between them. The thinner
silicon layer is etched on both sides to create an integrated vacuum
reference chamber for the absolute pressure sensor and to form a
pressure sensitive silicon diaphragm. The thicker silicon layer is the
rigid base plate of the sensor and it is clad with a glass dielectric. The
thinner piece of silicon is electrostatically bonded to the glass surface
to form a strong and hermetic bond. Thin film metallization has been
deposited to form a capacitor electrode inside the vacuum reference
chamber; the other electrode is the pressure sensitive silicon
diaphragm.
Vacuum gap
®
pressure sensor
Silicon
Glass
Silicon
The coefficients of thermal expansion of silicon and glass materials
used in the BAROCAP® pressure sensor are carefully matched
together in order to minimize the temperature dependence and to
maximize the long-term stability. The BAROCAP® pressure sensor is
designed to achieve zero temperature dependence at 1000 hPa and its
long-term stability has been maximized by thermal ageing at an
elevated temperature.
The BAROCAP® capacitive pressure sensor features a wide dynamic
range and no self-heating effect. The excellent hysteresis and
repeatability characteristics are based on the ideal spring
characteristics of single crystal silicon. In the BAROCAP® pressure
sensor, the silicon material is exerted to only few percent of its whole
elastic range.
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Measurement principle
The measurement principle of the PTB220 series digital barometers is
based on an advanced RC oscillator with three reference capacitors
against which the capacitive pressure sensor and the capacitive
temperature compensation sensor are continuously measured. A
multiplexer connects each of the five capacitors to the RC oscillator
one at a time and five different frequencies are measured during one
measurement cycle (FIGURE 2-2 )
CC
PT
CC
13
R
C
2
F
out
FIGURE 2-2 RC-oscillator with five capacitors
The RC oscillator is designed to attenuate changes in stray impedance
and to achieve excellent measurement stability with time. Vaisala’s
electronic measurement principle emphasizes in the first place
stability over a wide environmental temperature and relative humidity
range and over a long period of time; yet it can achieve fast
measurement speed and high resolution at the same time.
In the fast measurement mode, a special measurement algorithm is
used. In this mode only the frequency from the BAROCAP
pressure
sensor is measured continuously while the frequencies from the three
reference capacitors and from the thermal compensation capacitor are
updated only every 30 seconds. This is quite justifiable as the changes
in the reference capacitors can be considered negligible over any
periods of time, and the internal temperature of the barometer remains
stable enough over a few tens of seconds. The fast measurement mode
achieves a speed of ten measurements per second at 1 pascal
resolution. Each measurement represents the pressure average during
the last 100 ms. When the reference frequencies are measured every
30 seconds the outputting stops for a short moment and typically one
measurement is lost during this time. The fast measurement mode can
be used only in barometers with one pressure transducer and in full
duplex communication.
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CHAPTER 2___________________________________________________ PRODUCT DESCRIPTION
Block diagram
The PTB220 series digital barometers consist of a CPU board and 1, 2
or 3 pressure transducers (P1, P2 and P3). The number of pressure
transducers is order specific and the configuration cannot be changed
by the user. Usually the pressure transducers are connected to the
same pressure port. However, in case of two pressure transducers, the
barometer can have also two pressure ports, one for each transducer.
The various hardware configurations are illustrated on page 77.
The PTB220 series barometers always have a RS 232C full duplex
and a bidirectional TTL level serial interface. In addition, the
barometers have either a pulse output interface or an RS 485/422 twowire half duplex serial interface. The RS 485/422 interface is a
separate optional module inside the barometer. This interface module
is order specified and installed at the factory only. There is also an
optional factory set analog output module available. A LCD display
with backlight is also a possible configuration option.
The block diagram of the PTB220 series barometers is shown in
FIGURE 2-3
FIGURE 2-3 Block diagram of the PTB220 barometers
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CHAPTER 3___________________________________________________________ GETTING STARTED
CHAPTER 3 GETTING STARTED
As the PTB220 series digital barometers always have an RS 232C
serial interface, the user is requested to use this interface when
operating the barometer for the first time. The RS 232C is the most
useful and reliable interface for commissioning the barometers with
various software settings.
The RS 232C serial interface of the PTB220 barometers does not
provide handshaking lines (such as DSR, CTS or DTR). If the host
system requires handshaking lines, appropriate external connections
have to be made in order to enable the communication with a PTB220.
See Appendix on page 81 for more details on how to connect the
handshaking lines.
NOTE
1. The sending of PTB220 is controlled with XON/XOFF (software
handshaking)
2. The buffer of the barometer can be cleared with <cr>.
The RS 232C serial interface and power supply pin assignment is as
follows:
5
FIGURE 3-1 9-pin female subD-connector
1234
89
67
PIN SIGNAL
2 TX
3 RX
5 ground for the RS 232C
7 ground for supply voltage
9 supply voltage (10...30 VDC)
FIGURE 3-2 RS 232C and power supply pins
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1
The factory settings of the PTB220 series barometers are the
following:
TABL E 3-1 Serial interface factory settings
Baud rate 9600
Parity even
Data bits 7
Stop bits 1
Duplex full duplex
After having made the electrical connections, switch the power on,
and the barometer responds indicating the barometer type and the
software version.
PTB220 / 2.02
>
The barometer is now ready to respond to any command, for example
to commands R, S or SEND (see page 43).
If there is a LCD display cover, at power-up the display will first show
the barometer type and the software version. Then it switches to
display the barometric pressure reading as defined with the DFORM
command. The keyboard of the display cover can be used to inspect
and change the parameters available (see page 51).
Should there be any problems please check the jumper settings in
connector X15 and the settings in dip switch S1 inside the barometer.
The settings should be as indicated in the figures below.
RX/RXD
RXD
TX
TXD
TXD
X15
FIGURE 3-3 Basic RS 232C jumper and dip switch S1 settings
ON
OFF
SW1
SW2
SW3
SW4
SW5
SW6
S
SW7
SW8
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CHAPTER 4_____________________________________________________________ COMMISSIONING
CHAPTER 4 COMMISSIONING
TABL E 4-1summarizes the commands used to commission the PTB220
series digital barometers. The commands are not case sensitive except
for the SCOM command.
TABL E 4-1 Commissioning commands
Function Command
sending mode SMODE
measurement mode MMODE
pulse mode settings PULSE
serial bus settings SERI
echo on / off ECHO
output format FORM
pressure resolution FORM
pressure trend FORM
pressure tendency FORM
error status FORM
stability indicator FORM
checksum FORM
height of height correction HHCP
error output format EFORM
display format DFORM
pressure and temperature units UNIT
averaging time AVRG
setting output interval INTV
address of the barometer ADDR
user specific SEND command SCOM
pressure stability indicator PSTAB
pressure alarm levels (HI and LO) PLARM
pressure difference limit PDMAX
keyboard locking KEYLOCK
The commissioning commands can be divided in two sections: the
operating mode commands and the software setting commands.
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Operating modes
The first thing to do is to select the desired sending mode for the
barometer. This is done with the command SMODE. There are
available the normal or the fast measurement mode or the pulse output
mode. These selections are made with MMODE and PULSE
commands.
SMODE Selecting the sending mode
SMODE x <cr>
where:
x = STOP, RUN, SEND or POLL
The SMODE command is used to set or inspect the sending mode of
the barometer. The PTB220 series digital barometers have four
sending modes: STOP, RUN, SEND and POLL.
In STOP mode (see page 43), after power-up the barometer outputs its
type and software version and then waits for further commands.
In RUN mode (see page 43), continuous outputting starts
automatically from power-up.
In SEND mode (see page 50) a single message is automatically output
after power-up.
POLL mode (see page 48) allows the communication with multiple
barometers or other digital instruments connected to one serial bus.
Echo is automatically off in the POLL mode.
Examples:
>smode <cr>
Serial mode : STOP
>smode run <cr>
Serial mode : RUN
>smode send <cr>
Serial mode : SEND
>smode poll <cr>
Serial mode : POLL
>smode stop <cr>
Serial mode : STOP
>reset<cr>
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CHAPTER 4_____________________________________________________________ COMMISSIONING
1
NOTE
Remember to give the RESET command to initialize the new sending
mode.
MMODE Selecting the measurement mode
MMODE x <cr>
where:
x = NORMAL or FAST
The MMODE command is used to set or inspect the measurement
mode of the barometer. In the normal measurement mode, the
barometer measures the capacitance of each of the five capacitive
components of the pressure transducer (see page 6). This is the
standard operating mode of the PTB220 series digital barometers.
In the fast measurement mode, the barometer measures mainly the
capacitance of the BAROCAP pressure sensor and results in a faster
measurement speed (approximately 10 measurements per second).
This measurement mode can be used only with the barometers having
one pressure transducer and full duplex communication.
MMODE selection is protected by switch SW4 (see FIGURE 4-1). The
switch SW4 is normally in DISABLE position (OFF). Turn the switch
to ENABLE position (ON) to be able to make a new MMODE
selection.
ON
S
OFF
SW3
SW5
SW1
FIGURE 4-1 Switch SW4 in ENABLE position (ON)
SW2
SW4
Example of selecting the fast measurement mode:
>mmode <cr>
Meas mode : NORMAL
>mmode fast <cr>
Meas mode : FAST
>mtim 32 <cr>
SW6
SW7
SW8
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Mtim : 32
>filt off <cr>
Filter : OFF
>reset <cr>
NOTE
Remember to give the RESET command to initialize the new
measurement mode.
The measurement time (mtim) setting of 32 is recommended in order
to achieve the best output stability at the speed of 10 measurements
per second. The filter command ensures that no numerical filtering is
performed in the fast measurement mode. The MTIM and FILT
commands are used only together with the MMODE FAST command.
In the NORMAL measurement mode, the AVRG command replaces
the MTIM and FILT commands in the PTB220 series digital
barometers.
NOTE
Always remember to return the switch SW4 to write DISABLE
position (OFF).
PULSE Selecting the PULSE output mode
PULSE a s r o <cr>
where:
a=ON or OFF (activation/deactivation)
s = SLOW or FAST (speed)
r = LOW or HIGH (resolution)
o = pressure offset (hPa/mbar units only)
The PULSE command is used to activate or deactivate the pulse ouput
mode and to set or inspect the desired parameters. SLOW/FAST
selection affects the pulse rate: SLOW speed equals to 5 kHz pulse
rate and FAST speed equals to 50 kHz pulse rate. LOW resolution
equals to 0.1 hPa/mbar pressure resolution and HIGH resolution
equals to 0.01 hPa/mbar pressure resolution. In order to minimize the
number of output pulses the user can define an offset pressure so that
pulse outputting starts from the selected pressure level.
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CHAPTER 4_____________________________________________________________ COMMISSIONING
NOTE
The pulse output mode can be used with hPa/mbar pressure units
only!
Example of software settings for the pulse output mode:
>pulse <cr>
OFF SLOW LOW 0.0
>pulse on slow low <cr>
ON SLOW LOW 0.0
>pulse on fast high -800 <cr> (note the minus sign)
ON FAST HIGH -800.0
>pulse off <cr>
OFF FAST HIGH -800.0
>
The operation of pulse output mode can be tested through the RS232C
serial interface using the PTEST command (see page 69).
In addition to the above mentioned software settings, the user must
finally set the switch SW3 to position ON (see Hardware settings on
page 33) for the barometer to start to wait for an external trigger pulse.
NOTE
See page 83 for quick reference information on how to set and use the
pulse output mode of the PTB220 series digital barometers.
In case of an error in a PTB220 series barometer, there will be no
pulse output from the barometer despite an external trigger pulse.
This error handling technique ensures that a host system cannot
receive erroneous pressure readings from a PTB220 series
barometer.
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Software settings
SERI Serial bus settings
SERI b p d s x <cr>
where: (* = factory setting)
b = baud rate (300, 600, 1200, 2400, 4800, 9600*)
p = parity (E = even*, O = odd, N = none)
d = data bits (7* or 8)
s = stop bits (1* or 2)
x = duplex (F = full* or H = half)
<cr> = carriage return is generated by the ENTER or RETURN
key of the host computer
The SERI command is used to set or inspect the serial bus settings of
the barometer.
Examples:
>seri <cr>
9600 E71F
>seri 1200N81H<cr>
1200 N81H
>reset <cr>
PTB220 / 2.02
>seri 2400 <cr>
2400 N81H
>seri F <cr>
2400 N81F
>reset <cr>
PTB220 / 2.02
>
Always give the RESET command after the SERI command to
activate the new serial bus settings.
The following bus settings do not work with the incorporated Intel
8051 microprocessor. They are modified by the barometer:
N 7 1 → N 7 2
E 8 2 → E 8 1
O 8 2 → O 8 1
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The RS485/422 interface of the PTB220 series digital barometers is a
non-isolated two-wire half-duplex interface. See page 93 for quick
reference information on how to use the RS485/422 interface of the
PTB220 series digital barometers.
ECHO Setting the serial bus echo on/off
ECHO x <cr>
where:
x=ONorOFF
The ECHO command is used to set or inspect the echoing condition of
the barometer. In OFF mode the barometer does not output the '>'
prompt character.
Examples:
>echo <cr>
Echo : ON
>echo off <cr>
Echo : OFF
...
echo on <cr> (text invisible)
Echo : ON
>
FORM Defining the output format
The FORM command is used to set or inspect the output format of the
barometer. See the examples in the next page.
FORM <cr>
The user can define the following fields into the output format:
amount of decimals give number of decimals before a
quantity. Giving 4.2 before the
pressure quantity outputs a reading
with the following form: 1013.12
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pressure quantities P1 (reading of the transducer 1),
P2 (transducer 2), P3 (transducer
3), P (average)
height corrected pressure HCP (see also page 25)
pressure trend *) TREND (three-hour trend)
pressure tendency A (see page 101 for details)
temperature quantities *) T1, T2, T3
pressure and temperature units UU, UUU, UUUU,UUUUU
address of the barometer ADDR (uses two characters)
error status ERR (uses three characters)
stability indicator OK (uses three characters)
checksums CS2, CS4
number fields n.m where: n = 0 - 9, m = 0- 9
text fields within “ “ characters
ASCII characters:
CR # r
LF # n
TAB # t
nnn ASCII code # nnn
*) The PTB220 barometer cannot output + sign for pressure trend or
temperature reading; a space is output instead.
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Examples of different ways of setting the output format:
1. To output the pressure reading.
>form <cr>
4.2P""UUUU #r #n
? <cr>
>send <cr>
1020.30 hPa
>
2. To output the transducer values (P1,P2,P3) separately and the
average value (P).
>form <cr>
4.2P""UUUU #r #n
?4.2P1""P2""P3""P""UUU#r#n<cr>
>send <cr>
1020.31 1020.32 1020.33 1020.32 hPa
>
3. To output pressure reading followed with three-hour trend.
>form <cr>
4.2P""UUUU #r #n
?4.2P""UUU""2.1TREND " " UUU #r #n <cr>
>send <cr>
1020.30 hPa **.* hPa (date not available)
>send <cr>
1020.30 hPa -1.2 hPa
4. To output pressure reading followed with three-hour trend and
pressure tendency.
>form <cr>
4.2P""UUUU #r #n
?4.2P""UUU""2.1TREND""UUU""A#r#n<cr>
>send <cr>
1020.30 hPa **.* hPa * (date not available)
>send <cr>
1020.30 hPa -1.2 hPa 7
>send <cr>
1020.30 hPa 1.2 hPa 2 (no + sign)
5. To output the pressure from tranducer P1 followed with
temperature reading.
>form <cr>
4.2P""UUUU #r #n
?4.2P1""UUU""3.1T1""UU#r#n<cr>
>send <cr>
1020.30 hPa 23.4 'C (no + sign)
>
VAISALA _________________________________________________________________________ 19
USER'S GUIDE_______________________________________________________________________
6. To output the average pressure reading in the units of inHg .
>form <cr>
4.2P""UUU#r#n
?2.4P""UUUU #r #n <cr>
>unit inHg <cr>
P unit : inHg
>send <cr>
30.1234 inHg
>
7. Adding a text field, giving the address and outputting the
pressure reading from a identified barometer.
>form <cr>
4.2P""UUUU #r #n
? "Barometer " ADDR""4.2P""UUU#r#n<cr>
>addr 7 <cr>
Address : 7
>send 7 <cr>
Barometer 07 1020.30 hPa
>
8. To output the average pressure reading and the error status.
>form <cr>
4.2P""UUUU #r #n
?4.2P""UUU""ERR#r#n<cr>
>send <cr>
1020.30 hPa 0 (no error found)
>send <cr>
1020.30 hPa 1 (some error has occurred)
>
9. To output the transducer values (P1,P2,P3) separately and the
average value (P). Indicates errors if the maximum pressure
difference between the transducers is exceeding the defined value.
The two-or three-digit error field in the end of the line is expressing
the error state of the transducers. Number 1 means error and number 0
normal state. The first digit shows state of transducer 1 (P1), second
digit shows state of transducer 2 (P2) and the third digit shows
transducer 3 (P3).
>form <cr>
4.2P""UUUU #r #n
?4.2P1""P2""P""UUU""ERR#r#n<cr>
>send <cr>
1020.30 1020.32 1020.31 hPa 00
>send <cr>
1020.30 1022.30 1021.30 hPa 11 (Pd max error)
>
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CHAPTER 4_____________________________________________________________ COMMISSIONING
>form <cr>
4.2P""UUUU #r #n
?4.2P1""P2""P3""P""UUU""ERR#r#n<cr>
>send <cr>
1020.30 1020.31 1020.32 1020.31 hPa 000
>send <cr>
1020.30 1022.31 1020.32 1020.31 hPa 010 (Pd max error)
>
>form <cr>
4.2P""UUUU #r #n
?4.2P1""P2""P3""P""UUU""ERR#r#n<cr>
>send <cr>
1020.30 1020.31 1020.32 1020.31 hPa 000
>send <cr>
1020.30 1022.31 1024.32 1022.31 hPa 111 (Pd max error)
>
10. To output the pressure reading and the stability state.
>form <cr>
4.2P""UUUU #r #n
?4.2P""UUUOK#r#n<cr>
>send <cr>
1020.30 hPa OK (good stability)
>send <cr>
1020.30 hPa (poor stability)
>
11. To output the pressure reading and the checksums.
>form <cr>
4.2P""UUUU #r #n
?4.2P""UUU""CS2#r#n<cr>
>send <cr>
1020.30 hPa BB
>
12. To output the pressure reading and the height corrected
pressure reading.
>form
4.2 P HCP #r #n
?4.2P""hcp#r#n
>send
1011.12 1012.30
>
VAISALA _________________________________________________________________________ 21
USER'S GUIDE_______________________________________________________________________
EFORM Defining the error output format
EFORM <cr>
The EFORM command is used to define the user specific error output
format for the serial interface. In case of an internal error, the
barometer outputs the message defined with the EFORM command
instead of the normal message defined with the FORM command. If
the EFORM command is not defined, the barometer uses the FORM
command definition with its optional error status fields.
Example of an EFORM definition:
>eform <cr>
? "ERROR" #r #n <cr>
>P <cr>
1002.93 hPa OK (correct operation)
>P <cr>
ERROR (incorrect operation)
>
Any previous EFORM definition may be removed with the following
command:
>eform * <cr>
>
DFORM Defining the display format
DFORM <cr>
The DFORM command is used to define the format for the optional
LCD display. The user can define the following fields into the display
format:
pressure quantities P1, P2, P3, P (average)
height corrected pressure HCP (see also page 25)
pressure trend *) TREND (three-hour trend)
pressure tendency A (see page 101 for details)
temperature quantities *) T1, T2, T3
pressure and temperature units UU, UUU, UUUU,UUUUU
error status ERR (uses three characters)
stability indicator OK (uses three characters)
number fields n.m where: n = 0 - 9, m = 0- 9
text fields within “ “ characters
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CHAPTER 4_____________________________________________________________ COMMISSIONING
*) The PTB220 barometer cannot output + sign for pressure trend or
temperature reading; a space is output instead.
There are two rows containing 16 characters each; the user can define
a maximum of 32 characters to be displayed. The field definitions are
defined in successive order so that the first 16 characters will be
displayed on the first row and the next characters on the second row.
The factory setting for the display format includes the pressure
reading and the stability indicator:
ENTCL
Any previous DFORM definition may be removed and the original
factory setting restored with the following command:
>dform * <cr>
>
Example of setting the display format to show pressure, stability
indicator, pressure trend and pressure tendency:
>dform <cr>
4.2P""UUUUU OK #r #n
?""4.2P""UUUOK"trend " 2.1 TREND""UUU""A
<cr>
>
In this case, the display will look similar to the following:
ENTCL
VAISALA _________________________________________________________________________ 23
USER'S GUIDE_______________________________________________________________________
The PTB220 series barometers will show * instead of numeric values
for pressure trend and pressure tendency for three hours from powerup.
In case of error in the barometer, the relevant error message will
automatically appear on the second line of the display. In this case,
any other information defined using the DFORM command will be
replaced with an error message.
By pressing the arrow button on the left, you get a display having a
horizontal bar display on the upper row. On the lower row there are
three values: the value on the left shows the lower limit of the pressure
range, the middle value shows the actual pressure and the value on the
right shows the upper limit of the pressure range.
24 ___________________________________________________________________ M210194EN-A
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