Rotronic HygroClip M22 Series User manual

HygroClip M22 Series
2-wire loop powered
humidity temperature transmitters
INSTRUCTION MANUAL
20020530

CONTENTS
Overview................................................................................................................................. 3
Operation................................................................................................................................5
Power supply........................................................................................................................................... 5
HygroClip S digital probe......................................................................................................................... 5
Temperature operating range and limits................................................................................................. 6
Humidity limits ......................................................................................................................................... 6
Temperature compensation of the humidity sensor................................................................................ 6
Output range............................................................................................................................................ 6
Output signals.......................................................................................................................................... 6
Installation.............................................................................................................................. 7
General recommendations...................................................................................................................... 7
Installation and wiring of the base plate.................................................................................................. 7
Installation and removal of the HygroClip S probe.................................................................................. 8
Installation of the electronics module.................................................................................................... 10
Maintenance......................................................................................................................... 10
Cleaning or replacing the dust filter of the HygroClip S ........................................................................ 10
Periodic calibration check of the probe................................................................................................. 10
Service connector.................................................................................................................................. 12
Extension cable for the HygroClip S (used with model M22W) ............................................................ 13
Calibration cable for the HygroClip S.................................................................................................... 13
Service cables....................................................................................................................................... 14
Probe simulators.................................................................................................................................... 15
Specifications ...................................................................................................................... 16
Appendix 1: Practical Advice for Measuring Humidity.................................................... 17
Appendix 2: Calibration ...................................................................................................... 17
Appendix 3: Accessories for the M22 Series.................................................................... 18
PLEASE, READ THIS FIRST
•Check the product for any physical damage that may have occurred during shipment. We
carefully pack and routinely insure all shipments. If any damage has occurred, it is your
responsibility to file a claim with the carrier, prior to returning the damaged product. Please
note that our warranty does not cover damage during shipment.
•Prior to installation, get fully familiarized with the operating limits of the product and with the
installation instructions provided in this manual.
•Do not remove the sensor protection (dust filter) from the probe. Both sensors (humidity and
temperature) can be mechanically damaged by careless removal of the protection.
•Identification labels (model number, output ranges, etc.): identification labels are located (a) on
the shipping box and (b) inside the electronics module, under the printed circuit board (pop
out the board to read the label).

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Overview
The HygroClip M22 series are 2-wire, loop powered transmitters used to measure humidity and
temperature in manufacturing areas, clean rooms, research laboratories and other industrial
applications. Linearized output signals (DC current) are provided for transmission over a length of
cable to a remote display, recorder, controller or data processing unit. The M22 series uses the
HygroClip S plug-in probe. This probe has two analog outputs that are used by the M22 to read the
probe data. The HygroClip S also features a digital input / output which is used during calibration.
Digital signal processing within the HygroClip S maintains accurate measurements over the entire
operating range.
Main Features:
•relative humidity and temperature measurement
•fully interchangeable ROTRONIC HygroClip S digital plug-in probe
•software-based probe calibration
•two linearized analog 4-20 mA outputs signals (loop powered)
•test connector for communication with the HygroPalm 3 indicator 1)
1) allows the HygroPalm 3 to read and / or calibrate the transmitter
The M22 series features a unique installation method that is both convenient and problem free. Each
M22 series transmitter includes a base plate and a plug-in electronics module. During installation, the
base plate is mounted first and wired without the electronics module. This is done at the same time as
general electrical work. During that time, the electronics module and probe can safely be stored away.
The M22 series was designed to simplify the task of field maintenance and to minimize any downtime:
- Operation of the M22 transmitter can be easily verified in the field by connecting a HygroPalm 3
indicator to the M22 service connector. This is done without interrupting the output signals.
- Calibration is entirely digital, without any potentiometer. In addition, the HygroClip S digital probe is
100% interchangeable: calibration data, sensor characteristics, serial number, etc. are retained
within a non-volatile memory. Should the probe require maintenance, it can be replaced in seconds
without any loss of accuracy and without requiring a recalibration of the M22 transmitter. ROTRONIC
offers easy-to-use software and accessories for in-house calibration of the HygroClip S. If you do not
wish to calibrate, or if the HygroClip S has to be replaced, use our unique exchange program. This
plan is supported by the ROTRONIC worldwide distribution network. The replacement probe is either
a brand new HygroClip S or a reconditioned probe with a brand new humidity sensor and dust filter.
- Should the electronic module develop a problem, it can easily be removed from the base plate and
replaced with another module without having to do any wiring work.

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The M22 series is available in the following configurations:
Model Measurement Circuit Type Installation
M22W %RH + Temperature 2-Wire Loop Powered Wall mount (surface) or
remote probe *)
M22D %RH + Temperature 2-Wire Loop Powered Duct mount
(through Wall)
*) remote probe requires an extension cable (see accessories)
M22W
M22D

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Operation
Power supply
Transmitters of the M22 series require a supply voltage of 10..35 VDC (depending on the load
connected to the output)
The minimum supply voltage can be determined as follows: V min = 10 V + 0.02 x Load (ohm). For the
maximum load of 500Ω, the minimum supply voltage is 10 + 0.02 x 500 = 20 VDC.
The maximum current consumption is 40 mA.
HygroClip S digital probe
HygroClip S
operating range -40 to 85ºC (-40 to 185ºF)
wire mesh filter 1)
length: 100mm (3.9"), d: 15mm (0.6")
1) Special environments may require using a foam filter (consult ROTRONIC).
The HygroClip S measures relative humidity with a ROTRONIC
HYGROMERTM C94 capacitive humidity sensor. This well proven
sensor offers exceptional durability and stability in all kinds of
environments. Temperature is measured with a precision RTD Pt100
sensor.
The ROTRONIC HygroClip S digital probe is highly accurate and is
calibrated entirely by means of software (no adjustment
potentiometers). Because calibration and other data are stored in the
probe non-volatile memory, the probe is fully interchangeable. When
the probe requires calibration or has to be repaired, it can be
replaced with another probe in a few seconds.
With the M22W (wall mount model), the probe can be separated from
the transmitter with extension cable MOK-xx-DAT05: (xx = 1, 2 or 5
meters / 3.2, 3.5 or 16.4 ft). The maximum separation is 5 meter.
M22W

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Temperature operating range and limits
The M22 series can operate within -40 to 60°C (-40 to 140°F) at the electronics.
The temperature operating range of the HygroClip S probe is -40…85°C (-40…185°F).
Operating the transmitter and/or its probe outside of the temperature limits can result in
permanent damage.
Humidity limits
As far as possible, avoid sudden condensation at the sensors. When measuring at high humidity,
condensation may occur on the humidity sensor due to a sudden difference in temperature with the
environment. This does not damage the sensor. However, this will produce an overflow reading (an
output signal of more than 100 %RH) for as long as condensation is present on the humidity sensor.
Temperature compensation of the humidity sensor
Practically every make of relative humidity sensor requires a compensation for the effect of
temperature on the humidity output signal in order to measure accurately over a wide range of
temperature conditions. In the specific case of an instrument using a capacitive sensor, compensation
is required because the dielectric characteristics of both the water molecule and the hygroscopic
polymer used in the sensor vary with temperature.
The HygroClip S probe uses the temperature data from the Pt100 RTD to provide automatic
compensation for the effect of temperature on the humidity sensor. The temperature compensation
uses normal room temperature as a reference. Because of this, calibration of the HygroClip S is done
at normal room temperature rather than at the temperature of operation at the sensor.
Output range
The range of the relative humidity output is 0 to 100%RH. The temperature output depends on the
range specified when ordering - see identification labels (a) on shipping box and (b) inside electronics
module under the printed circuit board.
Output signals
The M22 series provides two 4-20 mA output signals. These signals are linear and are consistent with
the requirements of most data/signal processing instrumentation (panel meter, controller, computer
card, etc.).
The M22 behaves as a variable source of current and adjusts the current flowing through the terminals
as a function of relative humidity and temperature. The output signal may be read with any current
sensing device having a maximum impedance of 250 ohms. When several devices are connected in
series with the transmitter, the resulting impedance should not exceed 250 ohms, wiring included.
If so desired, the loop of one of the signal can be left open without affecting operation of the other
output (humidity or temperature only).

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Installation
Do not unnecessarily remove the dust filter from the HygroClip probe. The sensors can easily
be damaged when not protected.
General recommendations
Relative humidity is extremely dependent on temperature. Proper measurement of relative humidity
requires that the probe and its sensors be at exactly the temperature of the environment to be
measured. Because of this, the location where you choose to install the probe can have a significant
effect on the performance of the instrument. The following guidelines should guarantee good
instrument performance:
a) Select a representative location: install the probe where humidity, temperature and pressure
conditions are representative of the environment to be measured.
b) Provide good air movement at the probe: air velocity of at least 200 ft/ minute (1 meter/second)
facilitates adaptation of the probe to changing temperature.
c) Avoid the following: (1) Close proximity of the probe to a heating element, a cooling coil, a cold or
hot wall, direct exposure to sun rays, etc. (2) Close proximity of the probe to a steam injector,
humidifier, direct exposure to precipitation, etc. (3) Unstable pressure conditions resulting from
excessive air turbulence.
d) Immerse as much of the probe as possible in the environment to be measured.
e) Prevent the accumulation of condensation water at the level of the sensor leads. Install the
probe so that the probe tip is looking downward. If this is not possible, install the probe horizontally.
Installation and wiring of the base plate
The base plate should be installed first, using screws with an approximate diameter of 5/32".
Installation Note (through wall installation and remote probes)
You may want to provide an orifice at a distance of about 3” from the probe of
the transmitter for future use by a reference probe and HygroPalm indicator.
The base plate of the standard M22 series transmitter is supplied with one
sealing cable grip. This cable grip provides effective sealing only with cables
having the proper outside diameter. Preferably, use a cable with an outside
diameter of 0.236 to 0.275 inch (6 to 7 mm) and with 18 AWG wires. Avoid
running the cables connecting the unit in the same conduit as 110 VAC power
cables. Depending on the installation, you may have to use a cable with
twisted pairs or a shielded cable to avoid electromagnetic interference.
In order to determine the maximum length of cable that can be used to connect the transmitter to other
devices, the first step is to find out what is the resistance per unit of length of the cable that you plan
on using. The maximum permissible cable length, connecting the unit to other devices, is determined

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by the total resistance resulting from the addition of the cable resistance and that of the devices
connected in series with the unit. This resistance should not exceed 250 ohms.
RHT V+V+
Base Plate Terminals Description
1 and 3
2
4
5 and 6
10…35 VDC (+)
temperature output
relative humidity output
not used
Note: it is not necessary to connect both terminals 1 and 3 to the plus side of the power supply. The
transmitter will operate normally with just one of these terminals connected.
Measuring humidity or temperature only:the humidity and temperature circuits of the M22 are
independent one from the other. Any output can be operated without closing the loop for the other
output.
We generally recommend grounding the (-) side of the power supply, especially if the electronics will
be subjected to a low humidity environment (35 %RH or less).
Installation and removal of the HygroClip S probe
Both the HygroClip S and the base of
the connector on the transmitter are
marked with a dot. The locking ring is
marked with 2 dots.
The probe can be inserted straight into
the connector when all dots are aligned.
When the dots are not aligned, the
probe should be rotated clockwise
during insertion.
After inserting the probe, turn the
locking ring clockwise to secure the
probe.

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Installation of the electronics module
Once the base plate has been
installed and wired, the
electronics module can be
inserted and secured with the
screws provided. The
transmitter is ready to operate.
Maintenance
Cleaning or replacing the dust filter of the HygroClip S
The dust filter should be cleaned from time to time, depending on the conditions of measurement.
Cleaning should be done without removing the filter from the probe. Clean the filter with a fine brush. If
this is not sufficient, the filter should be replaced. To do this, unscrew the filter from the probe.
Before putting on a new dust filter, check the alignment of both sensors with the probe. The wires that
connect the sensors to the probe are very thin and bend easily. If this happens, correct the alignment
by holding the sensor very gently with a pair of small flat nosed pliers.
Periodic calibration check of the probe
Long term stability of the ROTRONIC Hygromer humidity sensor is typically better than 1 %RH
per year. For maximum accuracy, calibration of the probe should be verified every 6 to 12
months. Applications where the probe is exposed to significant pollution may require more
frequent verifications.
Both the Pt 100 RTD temperature sensor and associated electronics are very stable and should
not require any calibration after the initial factory adjustment.
For routine calibration checks, the probe should be verified at one or two values of humidity. For
more details, see service connector, accessories - service cable and appendix 2 –
calibration
Note: the electronics module of the M22 transmitter should not require any field calibration and it can
be easily validated by using a probe simulator (see accessories). The electronics module cannot be
serviced in the field and should be returned to the factory if there is any problem.

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Service connector
Transmitters of the M22 series feature a keyed 10-pin service connector. This service connector can
be used to connect M22 transmitter to probe input 1 of the HygroPalm 3 indicator with a service cable.
For details, see accessories - service cable below.
Do not touch the T min and H min
potentiometers. These are for
factory adjustment only.
Pop out the
ROTRONIC label
to access the service
connector 10 8 6 4 2
9 7 5 3 1
Optional display
Service Connector Pin # Wire Color Signal
1 Temperature Lo
1)
2 Temperature Hi
1)
3 Humidity Lo
1)
4 Humidity Hi
1)
5 Ground
6 V+ (power to service cable)
7 Not Used
8 Not Used
9 Not Used
10 Digital signal from HygroClip S (DIO)
1) Pins 1 and 2, as well as pins 3 and 4, are connected to each side of a precision 49.9 ohm resistor (0.1%) which
is in series with the output current. With a signal of 4 .. 20 mA current output the voltage measured across pins
1 and 2 (or pins 3 and 4) is within the range of 200 … 998 mV. For additional explanations, see service cable.
The components used in the circuits of the M22 transmitter are very stable and should not exhibit
any noticeable long-term drift. The transmitter can be verified with a probe simulator (see
accessories below).Transmitters that have drifted should be returned to the factory for repair or
replacement.

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Accessories
Extension cable for the HygroClip S (used with model M22W)
MOK-xx-DAT05: (xx = 1, 2 or 5 meters)
Calibration cable for the HygroClip S
The MOK-03-WIN cable is used to calibrate the HygroClip S probe independently from the M22
transmitter. The MOK-03-WIN cable connects the HygroClip S probe to the COM port of a PC.
This cable is shipped together with the Rotronic HW3 software which is used to read and
calibrate the probe from the PC.
The requirements for using HW3 are as follows:
3 m
PC Pentium 233MHz or better
Windows
®95/98,Me, XP or NT or 2000®
Memory 64MB
Disk Space 20MB free
Drives CD ROM drive required
Monitor VGA or Super VGA
Resolution 1024 x 768 or higher (set to small fonts)
High Color 16Bit (256 Color minimum)
COM Port RS232 (COM 1-4)
Software HW3 (includes - MSIE 4.0 Browser - Adobe®Acrobat Reader)
MS Internet Explorer: for best viewing, set fonts to smallest
For more details see separate instruction manual provided with the HW3 software.

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Service cables
Service cable ACRL420 is used to connect the service connector of the M22 to probe input 1 of the
HygroPalm 3 portable indicator / calibrator.
The service cable allows to do one of the following:
a) Read the analog output signals of the M22 transmitter with the HygroPalm 3.
The analog signals are read in %RH and in
°C (or °F, depending on the configuration of
the M22 and HygroPalm).
Note: probe input 1 of the HygroPalm must be
configured with the HW3 software analog
signals (probe 1 = analog probe) as per the
instructions provided with the service cable.
In addition, probe input 1 must be made to
match the measuring range and temperature
unit of the M22 transmitter.
HygroPalm 3
ACRL420 service cable
Probe Input 1
analog
b) 1-point calibration of the digital signal of the HygroClip S probe with the HygroPalm
Reference
Probe
HygroPalm 3
ACRL420 service cable
Probe Input 1
digital
This is done against a reference probe
connected to probe input 2 of the HygroPalm
(1-point calibration only). See separate
HygroPalm manual for detailed instructions
regarding calibration.
Note: probe input 1 of the HygroPalm 3 must
be configured with the HW3 software to read
a digital probe.

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Y-adapter Cable
The Y-adapter cable ACRLYB5 splits the signal from the ACRL420 cable so as make a simultaneous
connection with both probe inputs of the HygroPalm 3 (probe 1: analog and probe 2: digital).
ACRLYB5
ACRL420 Probe input 2
HygroPalm
Probe input 1
HygroPalm
Service
connector
M22
a) Calibration of the digital signal of
the HygroClip S probe against a
known reference environment
with the HygroPalm 3. Select
probe input 2 - configured as a
digital input - on the HygroPalm,
before entering the calibration
mode.
b) Validation of the analog signals
from the M22 transmitter by
comparison with the digital signal
of the HygroClip S. This is done
by switching the HygroPalm
display between probe 1 (analog)
and probe 2 (digital).
HygroPalm 3
ACRLYB5
Y-adapter
ACRL420 service cable
Probe Input
2
Probe Input
1
known reference
environment
Probe simulators
A probe simulator can be plugged in place of the HygroClip S probe to generate fixed humidity and
temperature values. This is used to validate the electronics of the transmitter.
In principle, any combination of humidity and temperature can be ordered. The following example
shows some of the most common combinations:
HygroClip S35/25: 35%RH and 25°C (77°F).
HygroClip S50/25: 50%RH and 25°C (77°F).
HygroClip S80/25: 80%RH and 25°C (77°F).
Like the HygroClip S probe, the probe simulators provide both digital and analog output signals.

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Specifications
Probe (plug-in) HygroClip S
Operating limits at probe 0…100%RH and -40…85°C (-40…185°F)
Operating limits at transmitter 0...99%RH non condensing
-40...60°C (-40...140°F)
Standard humidity output range 0..100 %RH
Standard temperature output ranges 0..100°F or 0..100°C
Output signals (linear) 4-20 mA (max. load 250Ω)
Accuracy at 68..77°F (20..25°C) ± (0.5%RH + 1.5% of reading)
±0.5°F (±0.3°C)
Repeatability ±0.3%RH and better than ±0.2°F (±0.1°C)
Humidity sensor stability better than 1%RH over a year
Response time (without filter) 10 seconds (%RH and temperature)
Supply voltage 10..35VDC; 10V + 0.02 x Load
Electrical connections power / outputs cable grip and terminals 3)
probe input connector
Sensor protection Wire Mesh Filter
Housing material ABS
Housing dimensions (w/o probe) 154 x 72.5 x 48 mm (6.06 x 2.86 x 1.89”)
Weight 0.7 lbs (300 g)
Protection grade IP 65 / NEMA 4

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Appendix 1: Practical Advice for Measuring Humidity
The most common source of error when measuring relative humidity is a difference between the
temperature of the probe and the temperature of the environment. At a humidity condition of 50
%RH, a temperature difference of 1°C (1.8 °F) typically results in an error of 3 %RH on relative
humidity.
When the probe is mounted through a wall, avoid temperature errors by inserting as much of the
probe as possible in the environment to be measured. Whenever there is a large temperature
difference across the wall, you may have to insert not only the probe itself but also some of the
probe cable (cables do conduct temperature).
In extreme situations, condensation may occur on the sensors when the probe is colder than the
environment. As long as the humidity / temperature limits of the humidity sensor are not exceeded,
condensation does not alter the calibration of the sensor. However, the sensor has to dry out before
it can provide a valid measurement.
Non-moving air is an excellent insulator. When there is no air movement, surprising differences in
temperature and humidity can be observed over short distances. Air movement at the probe generally
results in measurements that are both faster and more accurate.
Appendix 2: Calibration
The following choices are available to calibrate the probe used with the M22 transmitter:
a) Calibration of the probe connected to the M22 transmitter:
This requires a HygroPalm 3 indicator, a service cable ACRL420 as well as a Y-adapter cable
ACRLYB5 (see accessories – service cables).
Note that the M22 transmitter must be powered up during calibration.
1) For calibration only: connect cable ACRLYB5 to probe input 2 of the HygroPalm 3. Probe input 1 of
the HygroPalm does not have to be connected. Select probe 2 on the HygroPalm prior to calibrating.
2) Calibration and control of the analog output signals: connect cable ACRLYB5 to both probe inputs
of the HygroPalm 3. Probe input 1 of the HygroPalm must be configured to accept an analog probe as
per the instructions provided by Rotronic together with the ACRL420 service cable. Configuration of
the HygroPalm requires a PC with the Rotronic HW3 software installed. Both current loops of the M22
transmitter should be closed. To calibrate the probe connected to the M22 transmitter, select probe 2
on the HygroPalm and enter one of the calibration modes the HygroPalm (1-point calibration, multi-
point calibration). After returning the HygroPalm to its normal operating mode, the analog outputs of
the transmitter can be verified by selecting probe 1 (analog outputs) or probe 1 (digital signal from the
probe connected to the M22 transmitter) on the HygroPalm display.
Detailed calibration instructions are provided separately in the HygroPalm manual.
b) Calibration of the probe removed from the M22 transmitter:
This requires a PC with the optional HW3 software and the MOK-03-WIN calibration cable (separate
instructions are provided with the HW3 software).

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Appendix 3: Accessories for the M22 Series
Order Code Description
HW3 HW3 software (CD ROM)
HygroPalm 3 HygroPalm 3, field calibrator
ACRL420 Cable service connector M22 to HygroPalm 3 (probe input 1 )
ACRLYB5 Y-connection cable for use with the ACLR420 cable and HygroPalm 3.
Allows to calibrate the HygroClip S probe and to read the analog outputs of the
transmitter.
MOK-xx-DAT05 Probe extension cable for M22W (xx = 1, 2 or 5 meter)
MOK-03-WIN Calibration cable HygroClip probe with DAT05 connector to PC. Terminated with a 25-pin
SUB D connector. Converter 25-pin to 9-pin is supplied. Cable length 3 meter (9.8 ft).
9VDC adapter may be required (consult your local distributor)
HygroClip Sxx/yy HygroClip S probe simulator where xx = relative humidity in %RH and yy = temperature in
°C (fixed values)
EAxx-SCS humidity std, SCS certified, pack of 5
where xx = 00 (0 %RH)
= 05 (5 %RH)
= 10 (10 %RH)
= 11 (11 %RH)
= 20 (20 %RH)
= 35 (35 %RH)
= 50 (50 %RH)
= 65 (65 %RH)
= 75 (75 %RH)
= 80 (80 %RH)
= 95 (95 %RH)
ER-15 calibration device for HygroClip S probe