Vaisala CARBOCAP GMP231 User manual

M211501EN-E
User Guide
Carbon dioxide probe for CO2incubators
GMP231

PUBLISHED BY
Vaisala Oyj
Vanha Nurmijärventie 21, FI-01670 Vantaa, Finland
P.O. Box 26, FI-00421 Helsinki, Finland
[phone]
Visit our Internet pages at www.vaisala.com.
© Vaisala 2020
No part of this document may be
reproduced, published or publicly
displayed in any form or by any means,
electronic or mechanical (including
photocopying), nor may its contents be
modified, translated, adapted, sold or
disclosed to a third party without prior
written permission of the copyright holder.
Translated documents and translated
portions of multilingual documents are
based on the original English versions. In
ambiguous cases, the English versions are
applicable, not the translations.
The contents of this document are subject
to change without prior notice.
Local rules and regulations may vary and
they shall take precedence over the
information contained in this document.
Vaisala makes no representations on this
document’s compliance with the local
rules and regulations applicable at any
given time, and hereby disclaims any and
all responsibilities related thereto.
This document does not create any legally
binding obligations for Vaisala towards
customers or end users. All legally binding
obligations and agreements are included
exclusively in the applicable supply
contract or the General Conditions of Sale
and General Conditions of Service of
Vaisala.
This product contains software developed
by Vaisala or third parties. Use of the
software is governed by license terms and
conditions included in the applicable
supply contract or, in the absence of
separate license terms and conditions, by
the General License Conditions of Vaisala
Group.

Table of contents
1. Commands......................................................................................................... 7
1.1 Version information.......................................................................................... 7
1.2 Related manuals................................................................................................7
1.3 Documentation conventions............................................................................7
1.4 Trademarks........................................................................................................ 8
1.5 Patent notice..................................................................................................... 8
2. Product overview............................................................................................ 9
2.1 Introduction to GMP231....................................................................................9
2.2 Basic features and options.............................................................................10
2.3 GMP231 parts.....................................................................................................11
2.4 Operating principle of CO2measurement....................................................12
2.5 Environmental compensation........................................................................ 13
2.5.1 Pressure compensation........................................................................... 14
2.5.2 Temperature compensation ...................................................................14
2.5.3 Background gas compensations............................................................14
2.6 Probe startup................................................................................................... 14
2.7 Analog output overrange behavior...............................................................15
2.8 Safety................................................................................................................ 15
2.8.1 ESD protection......................................................................................... 16
2.9 Regulatory compliances................................................................................. 16
3. Installation........................................................................................................ 17
3.1 Thermal management.....................................................................................17
3.2 Avoiding condensation................................................................................... 17
3.3 Probe installation depth................................................................................. 17
3.4 Dimensions.......................................................................................................18
3.5 Recommended installation........................................................................... 20
3.6 Wiring...............................................................................................................22
3.7 Power supply...................................................................................................23
4. Vaisala Industrial Protocol........................................................................ 24
4.1 Overview of Vaisala Industrial Protocol.......................................................24
4.2 Serial interface settings................................................................................. 24
4.3 Physical interface............................................................................................24
4.4 Connecting with a computer........................................................................ 24
4.4.1 Installing driver for the USB service cable........................................... 25
4.4.2 Connecting to probe...............................................................................26
4.5 Serial commands............................................................................................ 27
4.6 Device information and status......................................................................29
4.7 Serial line output commands......................................................................... 31
4.8 Changing measurement settings..................................................................35
4.9 Configuring serial line operation.................................................................. 38
4.10 Calibration commands.................................................................................. 40
4.11 Configuring analog output........................................................................... 44
4.12 Other commands............................................................................................47
Table of contents
1

5. I2C interface....................................................................................................50
5.1 Overview of I2C interface.............................................................................. 50
5.1.1 Physical interface.................................................................................... 50
5.1.2 Communication parameters..................................................................50
5.1.3 Addressing...............................................................................................50
5.1.4 Timing........................................................................................................ 51
5.1.5 Status byte................................................................................................ 51
5.1.6 Checksum.................................................................................................52
5.1.7 Status word.............................................................................................. 52
5.2 Commands...................................................................................................... 54
5.2.1 Get_Interface_Version .......................................................................... 54
5.2.2 Get_Parameter........................................................................................ 55
5.2.3 Set_Parameter.........................................................................................57
5.2.4 Get_Parameter_Info............................................................................... 59
5.2.5 Adjust.........................................................................................................61
5.3 Adjusting measurement................................................................................ 63
5.3.1 1-point adjustment ................................................................................. 63
5.3.2 2-point adjustment................................................................................. 63
5.4 Data registers..................................................................................................64
5.4.1 Data formats............................................................................................64
5.4.2 Register table.......................................................................................... 64
6. Maintenance....................................................................................................69
6.1 Cleaning...........................................................................................................69
6.1.1 Chemical tolerance................................................................................. 69
6.2 Changing the filter......................................................................................... 69
6.3 Changing the silicone plug............................................................................70
6.4 Calibration and adjustment............................................................................71
6.4.1 Calibration setup...................................................................................... 71
6.4.2 Eect of environmental compensations.............................................. 73
6.4.3 Limits of adjustment............................................................................... 73
6.4.4 Adjustment types ................................................................................... 73
7. Operating with MI70 indicator................................................................ 75
7.1 Overview of MI70 support.............................................................................75
7.2 Connecting GMP231 to MI70 Indicator.........................................................75
7.3 Changing environmental compensation settings with MI70 indicator....75
7.4 Calibration and adjustment with MI70 indicator........................................ 77
7.4.1 1-point adjustment with an MI70-compatible reference probe.........77
7.4.2 1-point adjustment with a reference gas.............................................. 79
8. Troubleshooting............................................................................................. 81
8.1 Problem situations...........................................................................................81
8.2 Analog output error state...............................................................................81
9. Technical data................................................................................................ 83
9.1 GMP231 specifications....................................................................................83
9.2 Spare parts and accessories..........................................................................85
GMP231 User Guide M211501EN-E
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Online store.......................................................................................................87
Warranty............................................................................................................ 87
Technical support............................................................................................ 87
Recycling........................................................................................................... 87
Table of contents
3

List of figures
Figure 1 GMP231 installed through a chamber wall.................................................. 9
Figure 2 GMP231 parts.......................................................................................................11
Figure 3 CARBOCAPâsensor of the GMP231........................................................... 12
Figure 4 CO2measurement inside the incubator......................................................13
Figure 5 Probe installation depth..................................................................................18
Figure 6 Probe dimensions without silicone plug.................................................... 18
Figure 7 Probe dimensions with silicone plug...........................................................19
Figure 8 Electronics housing dimensions................................................................... 19
Figure 9 Attachment bracket dimensions................................................................. 20
Figure 10 Recommended installation............................................................................ 21
Figure 11 PuTTY terminal application...........................................................................27
Figure 12 Hardware schematic....................................................................................... 50
Figure 13 Changing the filter...........................................................................................70
Figure 14 Changing the silicone plug.............................................................................71
Figure 15 Inserting the calibration adapter over the filter.......................................72
Figure 16 CO2reading on MI70 screen......................................................................... 75
Figure 17 CO2 reading with Tcomp and Pcomp on MI70 screen...........................76
Figure 18 GMP231 compensation settings on MI70 screen.....................................76
GMP231 User Guide M211501EN-E
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List of tables
Table 1 Document versions (English)...........................................................................7
Table 2 Related manuals.................................................................................................. 7
Table 3 Applicable patents..............................................................................................8
Table 4 GMP231 connector pinout...............................................................................22
Table 5 Cable ....................................................................................................................23
Table 6 Default serial interface settings.................................................................... 24
Table 7 Basic serial commands.................................................................................... 27
Table 8 Advanced serial commands...........................................................................28
Table 9 ? Command........................................................................................................ 29
Table 10 SNUM command............................................................................................... 29
Table 11 VERS command................................................................................................ 30
Table 12 SYSTEM command........................................................................................... 30
Table 13 TIME command................................................................................................. 30
Table 14 HELP command.................................................................................................30
Table 15 R command......................................................................................................... 31
Table 16 S command.........................................................................................................32
Table 17 INTV command..................................................................................................32
Table 18 SEND command................................................................................................ 32
Table 19 FORM command................................................................................................33
Table 20 Output commands for FORM command....................................................34
Table 21 Modifiers for FORM command...................................................................... 35
Table 22 Compensation mode commands................................................................. 35
Table 23 ENV command...................................................................................................36
Table 24 STANDBY command........................................................................................ 38
Table 25 SMODE command.............................................................................................38
Table 26 SERI command.................................................................................................. 39
Table 27 ADDR command............................................................................................... 39
Table 28 SDELAY command...........................................................................................40
Table 29 ECHO command............................................................................................... 40
Table 30 CCO2 command................................................................................................40
Table 31 CDATE command...............................................................................................41
Table 32 CTEXT command.............................................................................................. 42
Table 33 CT command......................................................................................................42
Table 34 CP command......................................................................................................43
Table 35 ASEL command.................................................................................................44
Table 36 AMODE command............................................................................................44
Table 37 AOVER command.............................................................................................45
Table 38 ATEST command.............................................................................................. 46
Table 39 PASS command................................................................................................. 47
Table 40 OPEN command................................................................................................47
Table 41 CLOSE command.............................................................................................. 47
Table 42 ERRS command................................................................................................ 48
Table 43 RESET command.............................................................................................. 48
Table 44 FRESTORE command......................................................................................49
Table 45 GMP231 I2C Address.......................................................................................... 51
List of tables
5

Table 46 GMP231 Device Address...................................................................................51
Table 47 Timing................................................................................................................... 51
Table 48 Status Byte..........................................................................................................52
Table 49 Status word content.........................................................................................53
Table 50 Get_Interface_Version invoke message.....................................................54
Table 51 Get_Interface_Version response message................................................55
Table 52 Get_Parameter invoke message...................................................................55
Table 53 Get_Parameter response message..............................................................56
Table 54 Read CO2measurement sequence example.............................................56
Table 55 Set_Parameter invoke message....................................................................57
Table 56 Set_Parameter response message.............................................................. 58
Table 57 Set_Parameter return codes..........................................................................58
Table 58 Set compensation temperature sequence example............................... 59
Table 59 Get_Parameter_Info invoke message........................................................ 60
Table 60 Get_Parameter_Info response message................................................... 60
Table 61 Parameter data types......................................................................................60
Table 62 Parameter persistence......................................................................................61
Table 63 Adjust invoke message.....................................................................................61
Table 64 Adjust response message................................................................................61
Table 65 Adjustment subcommands............................................................................62
Table 66 Adjustment parameters.................................................................................. 62
Table 67 Adjustment return codes................................................................................62
Table 68 Data formats...................................................................................................... 64
Table 69 GMP231 register table......................................................................................64
Table 70 Possible problem situations and their remedies.......................................81
Table 71 Measurement performance............................................................................83
Table 72 Operating environment...................................................................................84
Table 73 Inputs and outputs........................................................................................... 84
Table 74 Mechanical specifications...............................................................................85
Table 75 Spare parts and accessories for GMP231....................................................85
GMP231 User Guide M211501EN-E
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1. Commands
1.1 Version information
This document provides information for installing, operating, and maintaining the Vaisala
CARBOCAPâCarbon Dioxide Probe GMP231.
Table 1 Document versions (English)
Document code Date Description
M211501EN-E April 2020 • Corrected initial CRC calculation value in section
Checksum (page 52)
• Updated examples in sections Get_Parameter
(page 55) and Set_Parameter (page 57)
• Updated section GMP231 specifications (page 83)
• Updated document to new visual appearance
M211501EN-D December 2014 Applicable from software version 1.1.0 onward.
Updated section Status word (page 52).
M211501EN-C May 2014 Updated description for ENV command in section
Changing measurement settings (page 35).
1.2 Related manuals
Table 2 Related manuals
Document code Name
M211603EN GMP231 Quick Guide
1.3 Documentation conventions
Warning alerts you to a serious hazard. If you do not read and
follow instructions carefully at this point, there is a risk of injury or even death.
WARNING!
Caution warns you of a potential hazard. If you do not read and
follow instructions carefully at this point, the product could be damaged or
important data could be lost.
CAUTION!
Chapter 1 – Commands
7

Note highlights important information on using the product.
Tip gives information for using the product more eciently.
Lists tools needed to perform the task.
Indicates that you need to take some notes during the task.
1.4 Trademarks
CARBOCAPâis a registered trademark of Vaisala Oyj.
All other product or company names that may be mentioned in this publication are trade
names, trademarks, or registered trademarks of their respective owners.
1.5 Patent notice
This product is protected by the following patents and their corresponding national rights:
Table 3 Applicable patents
Patent issued by Patent number
United States Patent and Trademark Oce US 5,827,438
US 6,177,673
European Patent Oce EP0776023
EP0922972
German Patent and Trade Mark Oce 69615635
Japan Patent Oce 4263285
Finnish Patent Oce 112005
105598
GMP231 User Guide M211501EN-E
8

2. Product overview
2.1 Introduction to GMP231
Vaisala CARBOCAPâCarbon Dioxide Probe GMP231 is designed for incubator manufacturers
requiring accurate and reliable carbon dioxide measurements and sterilization durability at
high temperatures.
GMP231 probe is based on patented Vaisala CARBOCAPâtechnology and a new type of infra-
red light source. The probe can remain in place during high-temperature sterilization cycles
that heat the chamber interior to +180 °C. Special design of the probe enables easy installation
through the incubator wall and ensures that the sensor optics and electronics are separated
and thermally insulated.
Sensor performance is optimized at 5 %CO2measurement. GMP231 also has an internal
pressure sensor, which allows compensation of the measurement according to ambient
pressure. Since dust and most chemicals do not aect the measurement, and the eect of
water vapor can be compensated for, GMP231 is accurate and stable at CO2incubator
conditions.
Figure 1 GMP231 installed through a chamber wall
Chapter 2 – Product overview
9

2.2 Basic features and options
• CO2measurement range 0 … 20 %CO2.
• Temperature durability in standby mode up to +195 °C (+383 °F).
• Vaisala CARBOCAPâCO2sensor with excellent long-term stability.
• Measurement compensated for eects of pressure, temperature, and background gas.
Pressure compensation based on integrated pressure sensor.
• Heating to avoid condensation on optical elements.
• Analog output: one current output channel (0 … 20 mA or 4 … 20 mA).
• Digital output:
• I2C.
• RS-485 (non-isolated) with Vaisala Industrial Protocol.
More information
‣Operating principle of CO2 measurement (page 12)
‣Environmental compensation (page 13)
‣Thermal management (page 17)
GMP231 User Guide M211501EN-E
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2.3 GMP231 parts
3
2
4
1
5
678
Figure 2 GMP231 parts
1Electronics housing. Contains the main component board, including the digital pressure
sensor.
2Holes for M4 screws on both sides of the housing. Maximum screw depth 8 mm. Two
screws included, type BN 10649 M4.
3Type label on housing cover (not shown).
48-pin M12 connector.
5Probe body.
6Measurement cuvette with optics and CARBOCAPâCO2sensor.
7PTFE filter.
8Silicone plug for sealing the lead-through. Recommended accessory, suitable for
∅44 mm lead-throughs.
Do not open the electronics housing; there are no user serviceable
parts inside. All wiring is done through the M12 connector (4).
CAUTION!
More information
‣Wiring (page 22)
Chapter 2 – Product overview
11

2.4 Operating principle of CO2measurement
Vaisala CARBOCAPâsensor used in the GMP231 is a silicon-based, non-dispersive infrared
(NDIR) sensor for the measurement of gaseous carbon dioxide. It is especially designed to
tolerate high temperatures in standby mode, up to +195 °C (+383 °F). This allows it to be used
in applications that utilize high temperature for heat sterilization. The operating temperature
range of the sensor is 0 … +70 °C (+32 ... +158 °F).
2
3
4
1
Figure 3 CARBOCAPâsensor of the
GMP231
1Cuvette
2Mirror
3Window
4Sensor chips
The sensitivity to carbon dioxide is based on absorption of infrared light at a characteristic
wavelength. The light is emitted by a novel, silicon-based microchip emitter into the cuvette
which contains the gas to be measured. After reflection from the mirror, the light intensity is
measured with a thermopile chip at a wavelength chosen by a micromechanical Fabry–Pérot
interferometer (FPI) and a band pass filter. A hermetically sealed sapphire window is used to
protect the sensor chips from moisture and contamination. A heater chip is utilized to prevent
condensation in normal operation.
The carbon dioxide measurement consists of two steps: First, the FPI is electrically tuned so
that its pass band coincides with the characteristic absorption wavelength of carbon dioxide
and the signal is recorded. Second, the pass band is shifted to a wavelength where no
absorption occurs in order to get a reference signal. The ratio of these two signals, one at the
absorption wavelength and the other at the reference wavelength, gives the fraction of light
absorption from which the carbon dioxide concentration is calculated. The reference signal
compensates the possible eects of sensor aging and signal attenuation due to dirt on optical
surfaces, making the sensor very stable over time.
GMP231 User Guide M211501EN-E
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12
3 4
56
78910
Figure 4 CO2measurement inside the incubator
1Chamber wall
2Chamber interior
3Light source
4Band pass filter
5Ambient air (400 … 1000 ppm CO2)
6Light absorbed by CO2in the incubator gas
7Thermopile detector
8Fabry-Perot interferometer
9Sapphire window. Separates the sensor’s active components from the
measured environment.
10 Gold-plated mirror
2.5 Environmental compensation
GMP231 improves the CO2measurement accuracy by applying various environmental
compensations. GMP231 compensates for the eects of:
• Pressure
• Temperature
• Background gas oxygen (O2) content
• Background gas relative humidity (%RH)
Compensation parameters are configured on the order form when ordering the probe, and can
later be updated using serial commands, MI70 Indicator, or I2C protocol. If the probe is
integrated in a system that measures one or more of the compensation parameters, they can
be updated to the probe continuously.
Chapter 2 – Product overview
13

You can also turn o any of the compensations. In that case, GMP231 uses the default
compensation value that is mathematically neutral for the probe’s internal compensation
model.
For more information on the eect of the compensations on measurement accuracy, see
GMP231 specifications (page 83).
2.5.1 Pressure compensation
There is a pressure sensor on the component board of the GMP231 that provides a live
measurement of ambient pressure. GMP231 can compensate the CO2measurement based on
this pressure reading, or it can use a fixed setpoint. Using the GMP231’s own sensor is
recommended for most applications.
If pressure compensation is turned o, GMP231 uses the default compensation value of 1013.2
hPa.
2.5.2 Temperature compensation
GMP231 can measure the approximate temperature of the CARBOCAPâsensor for
compensation, or use a fixed setpoint. The temperature measurement is accurate enough to be
useful for compensation, and is recommended for use unless a dedicated temperature
measurement is available and can be regularly updated to the GMP231.
If temperature compensation is turned o, GMP231 uses the default value of +37 °C (+98.6 °F).
2.5.3 Background gas compensations
Compensation for background gas parameters are based on setpoint values only, as GMP231
has no internal measurement for oxygen concentration or humidity. The default setpoint
values are as follows:
• Oxygen concentration: 19.7 %O2
• Relative humidity: 93 %RH
If background gas compensations are turned o, GMP231 uses the value 0% for both.
2.6 Probe startup
When powered on, GMP231 starts up within 10 seconds. Measurements from the outputs
(digital and analog) become available during this time but note that they only reach specified
accuracy after a one minute warm-up period. For this reason, you should design the
incubator’s control system so that it does not rely on measurements from GMP231 during this
time.
Specifically note that the CO2reading rises to the correct reading as the sensor's
infrared emitter achieves operation temperature.
GMP231 User Guide M211501EN-E
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2.7 Analog output overrange behavior
Analog output of the GMP231 has a defined behavior when the values measured by the probe
are outside the scaled analog output range:
• Output is allowed to go 10% over the scaled range.
• Output is set to error state when measured value is more than 10% outside the scaled
range.
• Output resumes normal function when measured value returns to within 10% of the
selected range.
For example, consider a GMP231 with 0 ... 20 mA analog output, scaled to 0 ... 10 %CO2.
• When measured CO2rises above 10 %CO2, the output rises above 20 mA.
• The output keeps rising until the measurement is 11 %CO2, at which point the probe
outputs 22 mA.
• If the CO2level rises above 11 %CO2, the output enters the error state, which is 23 mA for
the 0 ... 20 mA output.
This overrange and error state behavior is specific to the analog output, and does
not aect the readings provided by the digital outputs.
You can change the analog output overrange behavior using the AOVER command.
More information
‣Analog output error state (page 81)
2.8 Safety
The probe delivered to you has been tested for safety and approved as shipped from the
factory. Note the following precautions:
When returning a product for calibration or repair, make sure it
has not been exposed to dangerous contamination, and is safe to handle
without special precautions.
WARNING!
Do not modify the unit or use it in ways not described in the
documentation. Improper modification or use may lead to safety hazards,
equipment damage, failure to perform according to specification, or decreased
equipment lifetime.
CAUTION!
Chapter 2 – Product overview
15

Do not attempt to open the probe body. There are no user
serviceable parts inside the probe body.
CAUTION!
2.8.1 ESD protection
Electrostatic Discharge (ESD) can damage electronic circuits. Vaisala products are adequately
protected against ESD for their intended use. However, it is possible to damage the product by
delivering electrostatic discharges when touching, removing, or inserting any objects in the
equipment housing.
To avoid delivering high static voltages to the product:
• Handle ESD‑sensitive components on a properly grounded and protected ESD workbench
or by grounding yourself to the equipment chassis with a wrist strap and a resistive
connection cord.
• If you are unable to take either precaution, touch a conductive part of the equipment
chassis with your other hand before touching ESD‑sensitive components.
• Hold component boards by the edges and avoid touching component contacts.
2.9 Regulatory compliances
The probe is in conformity with the provisions of the following EU directives:
• EMC-Directive
• RoHS-Directive
The conformity is declared with using the following standards:
• EN 50581: Technical documentation for the assessment of electrical and electronic
products with respect to the restriction of hazardous substances.
• EN 61326-1: Electrical equipment for measurement, control, and laboratory use – Immunity
requirements for equipment to be used in a basic EMC environment.
• EN 55032: Class B. Electromagnetic compatibility of multimedia and information
technology equipment – Emission requirements.
GMP231 User Guide M211501EN-E
16

3. Installation
3.1 Thermal management
GMP231 is designed to remain installed during typical heat sterilization cycles that raise the
chamber temperature to 180 °C (356 °F). Since 180 °C is the target temperature for
sterilization, it is likely that there are hotspots inside the chamber that are above this
temperature. Avoid installing the GMP231 near such hotspots, for example near heating
elements. Do not expose the GMP231 to temperatures higher than 195 °C / 383 °F.
The following considerations are most important for achieving the specified heat durability
and measurement stability:
• Only the sensor and its filter should be exposed to heat. The filter must be completely in
the heated chamber. The probe body must remain inside the unheated chamber wall so
that only the end of the probe body extends exactly 2.5 mm into the chamber.
• During the sterilization cycle, you must set the GMP231 to standby mode (turns o the
CO2measurement), or power o the probe completely. The GMP231 automatically stops
its measurement cycle if it detects a high temperature, but it is best if the incubator’s
control system sets the GMP231 to standby mode when the sterilization cycle is started.
• The installation tube must be sealed from the chamber side to limit heat conduction, and
to prevent CO2in the chamber from entering the probe. Vaisala recommends a 44 mm
diameter installation tube together with Vaisala’s silicone plug.
• If the chamber wall contains heating elements, or has a construction where hot air is
circulated inside the wall, design the installation tube so that excessive heat is not
conducted to the GMP231.
3.2 Avoiding condensation
The sensor head of the GMP231 is heated during normal operation, which prevents
condensation from forming inside the filter and on the optical surfaces. The heating is not on
when GMP231 is in standby mode or unpowered. For this reason, keep the probe powered and
operating when the incubator is in use and humidity inside the chamber is high.
Correct installation depth of the probe is also important for preventing condensation from
running to the sensor along the chamber wall.
3.3 Probe installation depth
GMP231 must be installed so that only the sensor element and the filter are inside the chamber.
If the probe is longer than the installation tube, the extra length should extend to the outside
of the chamber.
The installation depth must be 2.5 mm. This installation depth provides the specified heat
durability of the probe, and allows the silicone plug to seal the Ø 44 mm installation tube
properly.
Chapter 3 – Installation
17

2.5 mm
Figure 5 Probe installation depth
3.4 Dimensions
163
118.5
Screw BN 10649 M4 x 8 mm
(for 1 mm thick sheet metal
attachment)
1121
Ø 30.2
1.3°
Ø 19
Ø 24.8
Position only the filter
inside the heated chamber
Figure 6 Probe dimensions without silicone plug
GMP231 User Guide M211501EN-E
18