Vaisala HMP240 User Manual
HMP240 SERIES
TRANSMITTERS
User's Guide
M210300en-A
June 2002
Vaisala Oyj 2002
No part of this document may be reproduced in any form or by any means,
electronic or mechanical (including photocopying), nor may its contents be
communicated to a third party without a prior written notice of the copyright
holder.
The instruction manuals may be changed without prior notice.
HMP240 series
M210300en User's guide
Contents
1. PRODUCT DESCRIPTION.......................................................................................... 5
2. ADVANTAGES OF A WARMED SENSOR HEAD........................................................7
3. INSTALLATION .......................................................................................................... 8
3.1 Selecting the place of installation .................................................................8
3.2 Mounting ........................................................................................................9
3.2.1 Mounting the HMP243.......................................................................9
3.2.2 Mounting the HMP247.....................................................................11
3.3 Grounding ....................................................................................................13
3.4 Electrical connections .................................................................................15
3.4.1 Connection to a 24 VAC supply .......................................................16
4. COMMISSIONING.....................................................................................................17
4.1 Changing the parameters ............................................................................ 17
4.2 Security lock jumper....................................................................................17
4.3 Selecting the analogue outputs ..................................................................18
4.4 Connecting the RS 232C serial bus.............................................................20
4.4.1 Reverting to factory settings of the serial port..................................22
5. COMMANDS.............................................................................................................24
5.1 Commands and security lock jumper .........................................................24
5.2 LED commands............................................................................................25
5.3 Display/keypad commands ..........................................................................26
5.3.1 Display mode..................................................................................26
5.3.2 Command mode .............................................................................26
5.3.3 Entering numbers............................................................................26
5.3.4 Analogue output commands............................................................ 27
5.3.4.1 Selecting the output (mA/V) ............................................................27
5.3.4.2 Selecting and scaling the analogue output quantities ......................28
5.3.5 Output via the serial bus .................................................................29
5.3.5.1 Turning the serial interface echo ON/OFF.......................................29
5.3.5.2 Serial bus settings...........................................................................29
5.3.5.3 Setting the transmitter address .......................................................30
5.3.5.4 Selecting the output units................................................................31
5.3.5.5 Selecting the calculation mode ........................................................31
5.3.6 Output modes .................................................................................31
5.3.6.1 Setting the serial interface operation mode .....................................32
5.3.7 Others.............................................................................................33
5.3.7.1 Setting the averaging time............................................................... 33
5.3.7.2 Setting the pressure for mixing ratio and wet bulb
calculations.................................................................................33
5.3.7.3 Setting the date...............................................................................34
5.3.7.4 Setting the time...............................................................................34
5.3.7.5 Heat on / heat off command............................................................35
5.4 Serial commands..........................................................................................35
5.4.1 Analogue output commands............................................................ 35
5.4.1.1 Setting the analogue outputs ...........................................................35
5.4.1.2 Selecting and scaling the analogue output quantities ......................36
5.4.1.3 Scaling the analogue outputs ..........................................................36
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User's guide M210300en
5.4.2 Output via the serial bus................................................................. 36
5.4.2.1 Starting the measurement output.................................................... 36
5.4.2.2 Stopping the measurement output.................................................. 36
5.4.2.3 Outputting the reading once............................................................ 37
5.4.2.4 Setting the output interval for the RUN mode .................................. 37
5.4.2.5 Serial bus settings.......................................................................... 37
5.4.2.6 Selecting the output units ............................................................... 38
5.4.2.7 Setting the averaging time.............................................................. 38
5.4.2.8 Setting the transmitter address....................................................... 39
5.4.2.9 Setting the calculation mode........................................................... 39
5.4.2.10 Resetting the transmitter ................................................................ 39
5.4.3 Operating the transmitter via the serial bus..................................... 40
5.4.3.1 Setting the serial interface.............................................................. 40
5.4.3.2 OPEN & CLOSE............................................................................. 41
6. CALIBRATION ......................................................................................................... 42
6.1 Humidity calibration.................................................................................... 42
6.1.1 One point humidity calibration......................................................... 43
6.1.1.1 With serial commands.................................................................... 44
6.1.1.2 With display / keypad commands................................................... 44
6.1.1.3 With LED commands ...................................................................... 45
6.1.2 Two point humidity calibration......................................................... 45
6.1.2.1 With serial commands.................................................................... 45
6.1.2.2 With display / keypad commands.................................................... 46
6.1.2.3 With LED commands ...................................................................... 47
6.1.3 Humidity calibration procedure after sensor change........................ 48
6.1.3.1 With serial commands.................................................................... 48
6.1.3.2 With display / keypad commands.................................................... 48
6.1.3.3 With LED commands ...................................................................... 49
6.1.4 Humidity calibration table................................................................ 50
6.2 Temperature calibration.............................................................................. 50
6.2.1 One point offset calibration............................................................. 51
6.2.1.1 With serial commands.................................................................... 51
6.2.1.2 With display / keypad commands.................................................... 51
6.2.1.3 With LED commands ...................................................................... 51
6.2.2 Two point temperature calibration................................................... 52
6.2.2.1 With serial commands.................................................................... 52
6.2.2.2 With display / keypad commands.................................................... 53
6.2.2.3 With LED commands ...................................................................... 53
6.3 Calibration of analogue outputs................................................................. 54
6.3.1 With serial commands.................................................................... 54
6.3.2 With display / keypad commands.................................................... 54
6.3.3 With LED commands ...................................................................... 55
7. MAINTENANCE........................................................................................................ 56
7.1 Reference measurements ........................................................................... 56
7.2 Self-diagnostics........................................................................................... 56
7.3 Replacing the composite sensor................................................................ 57
7.4 Temperature channel (additional) adjustment with Pt 100 simulators..... 57
7.4.1 With serial commands.................................................................... 58
7.4.2 With display commands.................................................................. 58
7.4.3 With LED commands ...................................................................... 58
7.5 Temperature channel adjustment with Pt 100 simulators (composite sensor)
...................................................................................................................... 59
7.5.1.1 With serial commands.................................................................... 60
7.5.1.2 With display commands.................................................................. 60
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HMP240 series
M210300en User's guide
7.5.2 With LED commands ......................................................................60
7.6 Measurement of output currents using test points....................................60
7.7 Adjusting the contrast of the display..........................................................61
8. TECHNICAL DATA ...................................................................................................62
8.1 Dewpoint temperature .................................................................................62
8.2 Temperature (with additional T sensor head).............................................63
8.3 Calculated variables ....................................................................................63
8.3.1 Relative humidity (with additional T sensor head)............................63
8.3.2 Accuracy of other calculated variables ............................................64
8.4 Outputs .........................................................................................................65
8.5 Electronics ...................................................................................................65
8.6 Mechanics ....................................................................................................66
8.7 Electromagnetic compatibility.....................................................................67
SPARE PARTS AND ACCESSORIES...............................................................................68
APPENDIX 1: SERIAL COMMANDS ................................................................................69
APPENDIX 2: INSTALLING AND USING THE RS 485/422 SERIAL PORT MODULE ......91
APPENDIX 3: INSTALLING AND USING THE DIGITAL CURRENT LOOP MODULE ....102
APPENDIX 4: ERROR MESSAGES ................................................................................110
APPENDIX 5: CALCULATION FORMULAS ...................................................................116
APPENDIX 6: HMP240 WIRING DIAGRAM....................................................................118
APPENDIX 7: RE-GAINING............................................................................................119
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M210300en User's Guide
1. PRODUCT DESCRIPTION
The HMP240 transmitter is a microprocessor based instrument for the
measurement of dewpoint temperature especially in high humidities and/or
fast changing temperatures. The dewpoint temperature is measured through
relative humidity and temperature. The dewpoint temperature, although a
calculated variable, is the primary reading obtained with the HMP240. As the
probe is equipped with the warming function, the relative humidity reading
obtained is not correct as such whereas the dewpoint temperature is. If the
temperature is below 0 °C, the user can select whether the transmitter
calculates dewpoint or frostpoint reading; as default, the transmitter calculates
frostpoint.
The transmitter can be ordered with one or two sensor heads. If the transmitter
has only a humidity sensor head, it can output the dewpoint temperature or the
mixing ratio. If the transmitter is ordered with an additional temperature head,
the user can choose the output from the following readings: dewpoint, relative
humidity, ambient temperature, dewpoint difference (= ambient temperature dewpoint), mixing ratio, absolute humidity, and wet bulb temperature. The
configuration that the user completes in the order form determines the
available readings. The transmitter has two analogue outputs and can be
connected to a serial bus via the RS 232C interface or through an RS 485/422
serial module or a digital current loop module.
There are various possibilities for the configuration of the transmitter. It can
have either a blank cover, or a cover with a local display and keypad with
which to operate the transmitter. Two analogue output signals are selected
from the measured and calculated quantities; the signals can be scaled and the
measurement ranges changed. The HMP240 can be supplied with two, five or
ten meter sensor head cables.
The dewpoint measurement range is -40...+100 °C. The range depends on the
desired accuracy because the dewpoint is calculated through the RH and the T
readings (see Chapter 8). The analogue temperature output can be scaled quite
freely, for example -20...+60 °C can be set to correspond to 0...10 V. The
relative humidity, absolute humidity, dewpoint difference, mixing ratio and
wet bulb temperature ranges are also scalable.
In some specific applications, the sensor gain may gradually decrease because
of an interference caused by some particular chemicals present in the ambient.
These changes can be recovered with an optional re-gaining function.
The transmitter is equipped with a composite humidity and temperature
sensor; the operation of the HUMICAP®KC humidity sensor is based on
changes in the capacitance of the sensor as its thin polymer film absorbs water
molecules.
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HMP240
User's Guide M210300en
Options
Additional T probe For the measurement of the ambient temperature and
for obtaining other quantities in addition to
dewpoint temperature and mixing ratio
Calculation variables
dewpoint difference, mixing ratio, absolute
humidity, wet bulb temperature
Serial interface RS 232C (standard), RS 485/422, digital current
loop module
Display cover cover with local display & keypad
Filters sintered filter, PPS grid with steel netting
Cable lengths 2, 5 or 10 meters
Installation aids
Installation kit for temperatures up to 180 °C
HMP243MIK Meteorological installation kit
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HMP240 series
M210300en User's Guide
2. ADVANTAGES OF A WARMED SENSOR HEAD
In some measurement applications, unwanted dew formation makes humidity
measurement difficult or even impossible. At a weather station, for example,
high humidity combined with rapidly changing outdoor temperature can
condense the water vapour in the air onto the sensor head. Until this dew
evaporates or dries, it is impossible to obtain a true reading. Dew formation is
also a problem in environmental chambers and in processes involving high
humidity, such as meat processing.
In some applications, rapid temperature changes are the source of difficulty.
Normally, relative humidity sensors must be at the same temperature as the
ambient air or the measurement is incorrect. At +20 °C and 90 %RH a difference of +1 °C causes an error of +6 %RH. This makes reliable humidity
measurements difficult in rapidly changing temperatures.
In other applications, the problem is a combination of both the dew formation
and rapid changes of temperature; a rapid rise in temperature can cause a
corresponding increase of water vapour in the ambient. In these conditions, the
temperature of the sensor head rises more slowly, and can remain below the
dewpoint of the ambient for a while. Dew then forms on the sensor head, and
it may take several hours or in the worst case, several days for the sensor to
recover from the condensation.
Vaisala's HMP240 dewpoint transmitter offers a reliable solution for humidity
measurement in all these demanding conditions. The humidity sensor head is
kept dry by warming it. As the measurement is fully temperature compensated,
changes in the process temperature do not delay the measurement. This means
that the response time of dewpoint measurement is proportional only to the
diffusion time of water molecules inside the sensor head.
The HMP240 has an excellent performance also at normal humidities and in
stable environments, but it will mostly be used in applications where very high
humidity can take place. In these kinds of applications, the use of traditional
transmitters has been restricted.
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User's Guide M210300en
3. INSTALLATION
3.1 Selecting the place of installation
The transmitter should be installed in a place that gives a true picture of the
environment or process and is as clean as possible. Air should circulate freely
around the sensor. If necessary, the transmitter can be installed in a place
where a hot spot may develop. However, cold spots should be avoided.
When the sensor head is installed in a duct or a process channel where the
temperature is different from the ambient temperature, insulate the point of
entry; this is particularly important if the transmitter is installed with the
sensor head pointing downwards. Installing the sensor head of the HMP240
vertically is not recommended because in high humidities, the humidity may
condence on the sensor head cable and then flow on to the sensor head.
When there is no alternative but to install the sensor head in the process
vertically, the point of entry must be carefully insulated. The cable must also
be allowed to hang loosely in order to prevent any water that possibly
condenses on the cable from running onto the sensor head.
Install the humidity sensor head in the process wherever possible. Avoid
sample flows where the gas temperature can drop below dewpoint
temperature; this might result in erroneous measurement readings. Install the
sensor head transversely against the direction of the process flow. If the
process temperature is much higher than that of the environment, the whole
sensor head and preferably part of the cable must be inside the process.
In duct or channel installations drill a hole ready for a reference meter. Plug
the reference hole tightly (see Figure 3.2).
Install the electronics housing away from possible steams escaping from the
process.
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HMP240 series
M210300en User's Guide
3.2 Mounting
3.2.1 Mounting the HMP243
133
humidity
sensor head
T-sensor head
(optional)
104
ø6.5
Cable length 2000,
5000 or 10000 mm
Sliding PTFE-sleeve for flange installation
and cable-gland installation
Figure 3.1 HMP243 transmitter with a humidity sensor head and an
additional T sensor head
When mounted on the side of a duct or channel, the sensor head must be inserted from the side (see Figure 3.2). If this is not possible and the sensor head
must be inserted from the top, the point of entry must be carefully insulated.
NOTE
The two sensor heads should be installed so that the
humidity sensor head does not warm the T sensor head,
i.e. the T sensor head is installed closer to the process
flow. When the RH reading is required, always install
the T sensor head in the place where you need the
reading from.
The HMP243 can be installed in ducts and channels with the help of the installation kit; the kit consists of a flange, a supporting bar for the sensor head
cable and screws for attaching the flange to the wall of a duct. With the help
of the installation kit the distance between the sensor head and the channel
wall can be easily adjusted. The range of adjustment is 100...320 mm; the
distance is measured from the tip of the sensor head to the flange.
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HMP240-series
h
User's Guide M210300en
duct wall
sealing (silicone)
flange
umidity sensor head
supporting bar
a plugged hole for reference
measurements
T-sensor head
(optional)
PTFE sleeve
Figure 3.2 Installing the sensor heads of the HMP243 in a channel
with the help of flanges and supporting bars
The sensor head can also be installed vertically.
PTFE-sleeve
a bushing (cable-gland)
(seal:Viton)
to be sealed
(silicone)
stain
or a
humidity sensor
head
T-sensor head
(optional)
when a bushing is used, its
size is selected according to
the diameter of the sensor
head; the diameter of the
cable is increased by using
e.g. silicon tape at the bushing
stainless steel
cable tie or a
similar fastener
m
h
h
10
Figure 3.3 Vertical installation of the HMP243 sensor heads
HMP240 series
M210300en User's Guide
3.2.2 Mounting the HMP247
HMP247 has a small size probe made of stainless steel. The sensor head
withstands temperatures -40...180 ºC (-40...356 ºF) and pressure up to 10 bar
(1MPa, 145 psi). The probe is suitable for applications where a mechanically
very durable leak proof probe is needed.
Pressure tight installations
A pressure tight installation can be done by using a probe head installation or
cable installation. Vaisala's cable gland HMP247CG is recommended for the
humidity probe's cable installation.
The different pressure tight installations of the HMP247 are shown in the
following pictures. In cases where the probe shall be positioned horizontally in
the measuring chamber (or in duct) a supportive thread bar set HMP247TBS
can be ordered from Vaisala (order code: HMP247TBS).
A) Probe head installation
1. Make hole with M20x1.5 thread
in the measurement chamber or
process wall. The smoothness of
the thread circle should be
R= 6.3 microm.
2. Install the cable gland
(EN50262, version A, example:
AGRO 1160.20.145) on the thread
of the process wall.
3. Push the probe through the
gland so deep that the backside of
the probe is flust with the cable
gland nut.
4. Tighten the cable gland nut,
the probe will lift up slightly.
B) Cable
installation with
Vaisala's
HMP247CG
∅13.6 mm ∅ 5.3 mm
Process pressure <
10 bar, temperature
according to the
cable's sealing
A) Pipe fitting
∅30/M20x1.5x13.5
B) Cable
installation with
Vaisala's
HMP247CG
Figure 3.4 HMP247 Pressure tight installations A) Probe head installation
B) Cable installation (cable gland: HMP247CG) .
11
HMP240
fitting and the cable.
User's Guide M210300en
Pressure tight installation with Vaisala's supportive thread bar
set HMP247TBS (cable gland HMP247CG included)
1. Make a hole with M20x1.5 to a wall or weld a pipe fitting
(∅30/M20x1.5x12mm) to a wall.
2. Install the cable gland's fitting body on the hole in the wall.
3. Thread the sensor head through the nut and press the cable
through the cutting line of the sealing.
4. Turn the supporting bars into the sensor head's threaded holes.
5. Turn the sleeve on the opposite end of the supporting bar and
trim to the right length.
6. Cut away the overage supporting bar with saw.
7. Press the sleeves together (with cable inside) and install the
sensor head to a process through the fitting body.
8. Tighten the cable gland nut.
For processes up to 120°C (248 °F). More detailed
instructions are included in the set.
Example of pressure tight temperature probe installation
(cable gland example: AGRO Nr. 1100.12.91.065, EN50262,
version A)
Process pressure < 7 bar,
temperature according to the cable
sealing
∅ 6.5 mm
Recommended support to
keep the probe in
horizontal position
Silicon glue between the PTFE
Cable gland
HMP247CG
12
Figure 3.5 HMP247 pressure tight installations with supporting bars.
HMP240 series
M210300en User's Guide
3.3 Grounding
A single electrical cable with a screen and three to ten wires is recommended
for power and analogue output/serial bus connections. The cable diameter
should be 7...10 mm.
The screen of the electrical cable must be grounded properly to achieve best
possible EMC performance. Recommended cable shield is done in the cable
gland as shown below.
• remove the brass disks, rubber ring and nut from the transmitter
housing
• strip 165 mm of the cable insulation, but leave 25 mm of the braid
visible
• slip the nut and rubber ring over the cable insulation
• slip the brass disk that has the bigger hole in it over the braid so that
it rests against the cable insulation
• slip the other brass disk over the wires to the middle of the braid
2
shielding tube
braid
brass disks
braid
brass
disks
rubber
ring
165
nut
cable
140
25
flexible wires 0.5 mm
(AWG 20), stranded wires
3
recommended
D = Ø 7...10 mm
(If the cable diameter is less
than 7mm, use a shrinking
tube or an adhesive tape)
• push back the braid and press it between the two brass disks to
achieve a full 360° grounding; the fold between the disks should have
the same diameter as the brass disks
• secure the braid with a shielding tube
• insert the wires into the transmitter housing through the gland
13
HMP240
User's Guide M210300en
• tighten the nut
• connect the wires into the screw terminals and fasten a cable tie
around the wires
cable tie
transmitter housing
gland
brass disks
rubber ring
nut
NOTE
When the cable is grounded as explained on the
previous page, the metallic parts of the sensor head, the
shield of its cable, the transmitter housing and the
shield of the signal cable to external system are all
connected to each other. After this the whole system
can be grounded from one point only. If the grounding
is made via several points (sensor head, transmitter
housing, signal cable), make sure that the different
groundings are made to the same grounding potential.
Otherwise harmful grounding currents may be
generated. If you do the grounding via the transmitter
housing, use one serrated lock washer between a mounting screw and the housing; the lock washer breaks the
paint on the housing.
14
HMP240 series
POWER SUPPLY
M210300en User's Guide
3.4 Electrical connections
CH1- and CH2- are conne cted
CH1+
CH1-
CH2+
together internally
CH2-
X2
X1
+ -
V
mA
+ -
V
mA
CURRENT/VOLTAGE
OUTPUTS
Do not use power supply
ground (-) as output signal
ground
24 V +
OPENED COVER OF THE
HMP 243
Figure 3.6 Electrical connections
Power supply 24 VDC
24 VAC (see Chapter 3.4.1)
Output signals 0...20 mA
4...20 mA
0...1 V
0...5 V
0...10 V
Power supply ground (-) is connected to the housing with parallel connection
of 15 nF capacitor and 300 kΩ resistor.
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HMP240
User's Guide M210300en
3.4.1 Connection to a 24 VAC supply
The HMP240 transmitter can also be connected to a 24 VAC supply without
an external rectifier. However, when more than one transmitter is connected to
one 24 VAC transformer, a common loop is formed and there is an increased
risk of a short-circuit. To avoid this, always use separate floating supply for
each transmitter (see Figure 3.7 A). However, if several transmitters have to
share one transformer, the phase (∼) must always be connected to + connector
in each transmitter (see Figure Figure 3.7 B).
A) NO COMMON LOOP FORMED - RECOMMENDED
HMP243 transmitter
24 VAC
24 VAC
HMP243 transmitter
B) COMMON LOOP FORMED -
HMP243 transmitter
24 VAC
supply voltage
Controller
supply voltage
supply voltage
signal output
signal output
NOT RECOMMENDED!
Controller
signal output
16
shared
common line
supply voltage
signal output
HMP243 transmitter
Figure 3.7 Connecting the transmitters to a 24 VAC supply (valid
also for the HMP247 transmitter).
HMP240 series
M210300en User's Guide
4. COMMISSIONING
When the HMP240 transmitter leaves the factory, its measurement ranges and
output signals have already been scaled according to the order form completed
by the customer. The unit is calibrated at the factory and ready to operate
when the power is turned on. If you take into use active current, voltage or
serial bus outputs, make these connections first; appendix 6 describes them in
detail.
NOTE
Make sure that the power is not turned on until cables
have been connected to screw terminals!
In transmitters with display, the software version appears for a few seconds
when the power is turned on. After this, measurement results appear
automatically. Should an error message appear on the display, consult
Appendix 4.
If your transmitter has a blank cover and the LED indicator inside the housing
lights up, consult Appendix 4 for further information.
4.1 Changing the parameters
If necessary, the user can subsequently change the measurement units between
metric and non-metric and select and scale the output signals with software
functions. This is done through commands, either utilizing the menus on the
local display or giving commands through the serial interface (see
Appendices). Most often the commands are used to change the settings of the
two analogue channels.
A limited range of commands can be given with the three press switches (up,
down, enter) inside the transmitter housing. There are four LEDs to indicate
the commands given with the up and down switches. All HMP240 units
incorporate these switches and LED indicators. LED commands can be used to
calibrate the transmitters (both humidity and temperature) or to calibrate the
analogue outputs.
If you need to change some functions, read the following chapters carefully.
4.2 Security lock jumper
Before the settings can be changed, the security lock jumper in connector X15
must be removed (see Figure 4.1). The security lock jumper makes it
impossible to change the transmitter settings by mistake.
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HMP240
OPENED COVER OF THE HMP 243
User's Guide M210300en
X15
CHANGE OF SETTINGS
DISABLED
Figure 4.1 Location of the security lock jumper
When the security lock jumper is connected, some commands are not available
(see Chapter 5).
Should the application require variables that are not included in the
configuration of the transmitter, the user is invited to contact Vaisala or a
Vaisala representative.
4.3 Selecting the analogue outputs
The HMP240 transmitter can be ordered ready with the current or voltage
outputs required. If the outputs need to be changed, move the jumpers in connector X15 into positions as shown in Figure 4.2.
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HMP240 series
OPENED COVER OF THE HMP 243
1
M210300en User's Guide
CH1
CH1
CH1
CH2
CURRENT OUTPUTS
0 ... 20 / 4 ... 20 mA
CH2
VOLTAGE OUTPUTS
0 ... 5 V / 0 ... 10 V
CH2
VOLTAGE OUTPUTS
0 ... 1 V
CH
CH2
CH1
CH2
CH1
CH2
CH1
CH1
CH2
CH2
CH1 0 ... 1 VOLTAGE OUTPUT
CH2 CURRENT OUTPUT
X15
Figure 4.2 Selecting the analogue outputs with jumpers
The software has to be informed which outputs are in use. This is done either
through the serial interface or the menus on a local display. The serial
command is AMODE and the display/keypad command "Mode ð Analog
outputs ð Mode" (see Chapter 5). For the scaling of the outputs, see serial
command ASCL and the display command "Mode ð Analog outputs ð
Scale".
All the jumpers are used only with the 0...1 V outputs. When other outputs are
in use, the spare jumpers are kept in connector X55.
19
HMP240
OPENED COVER OF THE HMP 243
User's Guide M210300en
X55
spare jumpers
OPENED COVER OF THE HMP 243
Figure 4.3 Spare jumpers
4.4 Connecting the RS 232C serial bus
RX
GND
TX
NC
X6
Figure 4.4 Serial bus connections
To connect a PC to the HMP240 transmitter via the RS 232C serial bus, one of
the following cables is required. The type of the cable depends on the terminal
and the connector type.
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HMP240 series
3
M210300en User's Guide
RXD
RXD
RXD
TXD
TXD
TXD
TX
GND
RX
TX
GND
RX
TX
GND
RX
HMP 24
PC
TERMINAL
D9S
D25S
D25P
2
5
3
4
6
7
8
3
7
2
5
6
8
20
3
7
2
Figure 4.5 Connection of cables
When the serial bus has been connected between the PC and the transmitter,
the PC is switched on. When using a PC, a terminal emulation programme
(e.g. Procomm Plus, Datastorm or Windows terminal) is started.
The factory settings for data transfer are:
• 4800 baud
• even parity
• 7 data bits
• 1 stop bit
• full duplex
NOTE
When the serial bus settings are changed, the transmitter has to be reset before the new settings become effective.
The processor does not allow the following combinations:
• no parity, 7 data bits, 1 stop bit: if this combination is given the
HMP240 programme will change the number of stop bits to 2
• even or odd parity, 8 data bits, 2 stop bits: if this combination is given
the programme changes the number of stop bits to 1
Refer to the manuals of the PC and the terminal emulation programme when
giving serial settings.
The RS 232C screw terminal cannot be used if an RS 485/422 serial module
or a current loop module is used. See Appendices 2 and 3 on how to install
and operate these modules.
21
HMP240
RX GND TX
User's Guide M210300en
In calibrating or changing the settings of the transmitter it can be more convenient to use the connector X17, if connector X6 is already in use. This connector, however, transfers only RS 232C signals. If an RS 485/422 serial port
module or a current loop module has been installed, it has to be removed before communicating through the X17 connector.
X17
Figure 4.6 Location and connections of connector X17
NOTE
Some PC computers can generate interferences to the
measured humidity and temperature values if the
transmitter and the PC are connected to different mains
outlets. To minimize the possibility of these interferences, always use the same mains outlet (same phase of
the mains electricity) for the PC and the power supply
of HMP240. This is especially the case when using the
serial line connector X17. The serial line connector X6
is more immune to these interferences than connector
X17.
4.4.1 Reverting to factory settings of the serial port
If the serial port settings are not known, no commands can be given via the
serial interface. The settings can be reverted to the factory settings by inserting
a jumper in connector X16. The jumper must be inserted when the power is
on!
X16
OPENED COVER OF THE HMP 243
Figure 4.7 Forcing the serial port settings back to factory settings
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HMP240 series
M210300en User's Guide
When the jumper is inserted the serial line factory settings become valid, but
only temporarily. The transmitter must be given new settings; otherwise
the transmitter uses the old, unknown settings after power-up. When the
new settings have been given, the transmitter must be reset. The jumper must
be removed before the transmitter is reset; if the jumper is in place when
power is turned on, the transmitter does not work.
After jumper insertion the transmitter is in STOP mode, ready to receive
commands.
The same method is used when the transmitter is in POLL mode and the user
has forgotten its address.
CAUTION
Inserting a jumper in any other place in connector X16
voids the guarantee of the transmitter.
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HMP240
User's Guide M210300en
5. COMMANDS
As the HMP240 transmitter is a microprocessor based device, its configuration
can be set to correspond to the specific needs of the user. This is done through
commands, either by utilizing the menus on the local display or by giving
commands through the serial interface (see Appendix 1). Most often the
commands are used to change the settings of the two analogue channels.
A limited range of commands can be given by using the three press switches up, down and enter - inside the transmitter housing. Four LEDs indicate the
command given with the up and down switches. LED commands can be used
to calibrate the transmitter (both humidity and temperature) or to calibrate the
analogue outputs.
A full range of commands can be given through the display/keypad or through
the RS 232C serial bus. The commands can be used e.g. to select and scale the
outputs, to calibrate the humidity and temperature channels as well as the
analogue outputs and to set the serial interface.
5.1 Commands and security lock jumper
In order to prevent any tampering with the transmitter settings, the transmitter
cannot be calibrated, the analogue outputs set or the analogue output
quantities selected or scaled unless the security lock jumper has been disconnected. The commands involved are:
• all LED commands
• display/keypad commands:
Cali ð RH T Ta
Analog outputs
Mode ð Analog outputs ð Mode
More ð More ð Frost
More ð Frost
• serial commands:
CRH, CT, CTA, FCRH, ACAL; AMODE, ASEL, ASCL, FROST,
FILT
In the following, the description of these functions is preceded with a reminder of the security lock jumper:
Scale
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Disconnect the security lock jumper!
HMP240 series
OPENED COVER OF THE HMP 243
M210300en User's Guide
5.2 LED commands
NOTE
If the transmitter has a display/keypad cover, the LED
commands cannot be used.
LED commands can be used to operate the transmitter in the field. These
commands can be used in humidity and temperature calibration and calibration
of the analogue outputs.
Open the housing and press any one of the three press switches. The LEDs
will light up for 2 - 3 seconds.
UP
DOWN
ENT
press switches
LEDs
Figure 5.1 Location of press switches and LEDs
Use the up and down switches (marked with arrows on the printed board) to
find the desired command code and acknowledge it with the ENT switch. The
command codes are (l = lit, ¡ = dark):
¡¡¡¡ (0) return to normal state
¡¡¡l (1) relative humidity calibration
¡¡l¡ (2) temperature calibration of the humidity sensor
head
¡l¡¡ (3) temperature calibration of the T sensor head
¡¡ll (4) calibration of analogue outputs
l¡¡¡ (8) relative humidity calibration after sensor change
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HMP240
User's Guide M210300en
5.3 Display/keypad commands
5.3.1 Display mode
In the display mode the transmitter outputs measurements on the display; different quantities can be scrolled with arrow keys. The first line is scrolled with
button σ and the second line with button τ; all selections are stored with
ENTER. The selected quantities appear on the display also after power failure.
After reset the transmitter is always in the display mode.
The display also shows error messages and alarms if they occur.
5.3.2 Command mode
Press the CL key to enter the command mode. The first display is the main
menu:
The commands can be scrolled with the arrow keys. The currently active
command flashes; a command is selected with the ENT key. When a menu is
displayed, either the first command or the currently valid setting flashes. The
CL key takes the transmitter back to the display mode.
5.3.3 Entering numbers
When numbers need to be entered into the transmitter programme (e.g. when
scaling or setting the analogue outputs, in calibration or when giving the
transmitter an address), the field is either empty or the currently valid figure is
displayed. Any previously given value is deleted with the CL key.
When the field is empty, a cursor blinks on the right side of the display.
Pressing the arrow keys makes either a blank ' ', a comma ',', a dash '-', a full
stop '.' or a number from '0' to '9' appear on the display. The right character is
selected with ENT; after that the number or numbers move left one step.
Entering numbers is ended with selecting a blank ' ' and pressing ENT. The
last character entered can be deleted with CL. If CL or ENT key is pressed
when the field is empty, the programme returns to the previous display.
With some commands (e.g. calibration) the figures are changed using the arrow keys. When an arrow key is pressed continuously for a while, the numbers
start changing at an increasing rate.
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HMP240 series
M210300en User's Guide
5.3.4 Analogue output commands
5.3.4.1 Selecting the output (mA/V)
Disconnect the security lock jumper!
• Select Mode in the main menu and Analog outputs in the Mode
menu:
• Select Mode ( mA / V ). The current settings for channel 1 are dis-
played:
• If the settings are correct, press ENT.
• If the settings need to be changed, press CL:
− the quantity (mA/V) starts flashing; it can be changed with the ar-
row keys and acknowledged with the ENT key
− the lower limit starts flashing
− acknowledge the lower limit with ENT or start changing it by
pressing CL; a new lower limit is given one character at a time
with the arrow keys
− the upper limit starts flashing
• acknowledge the upper limit with ENT or start changing it by pressing
CL; a new upper limit is given one character at a time with the arrow
keys
When channel 1 has been set, the programme goes on to channel 2; the procedure is the same as with channel 1.
NOTE
The analogue output jumpers must also be set to right
places (see Figure 4.2).
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HMP240
User's Guide M210300en
5.3.4.2 Selecting and scaling the analogue output quantities
Disconnect the security lock jumper!
• Select Mode in the main menu and Analog outputs in the Mode
menu:
• Select Scale. The quantity and scaling for channel 1 are displayed:
• If the settings are correct, press ENT.
• If the settings need to be changed, press CL:
− the quantity (RH, T, Td, dT, x, a, Tw) starts flashing; it can be
changed with the arrow keys and acknowledged with the ENT key
− the lower limit starts flashing
− acknowledge the lower limit with ENT or start changing it by
pressing CL; a new lower limit is given with the arrow keys
− the upper limit starts flashing
− acknowledge the upper limit with ENT or start changing it by
pressing CL; a new upper limit is given with the arrow keys
• When channel 1 has been set, the programme goes on to channel 2;
the procedure is the same as with channel 1.
Please note that the available selections are affected by the choice of output
parameters. Also make sure that the temperature measuring ranges are not
exceeded.
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