Vaisala HMI38, HMP36, HMP35 Operating Manual
HMI38 HUMIDITY DATA
PROCESSOR AND
HMP35/36/37E PROBES
Operating Manual
U063en-2.1
June 1998
Vaisala 1998
© Vaisala Oyj 1998
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.
Yleisjäljennös 06/1998
HMI38
U063en-2.1 Operating Manual
Contents
1. PRODUCT DESCRIPTION..........................................................................................1
2. TO BE NOTED WHEN M EASURING HUMIDITY ........................................................2
3. TAKING THE HMI38 INTO USE..................................................................................3
4. COMMISSIONING .......................................................................................................4
4.1. Initializing the probe locations......................................................................4
4.2. Connecting the analogue outputs.................................................................4
4.3. Connecting the RS 232C or RS 485 serial bus .............................................5
4.4. Summary of the factory settings ...................................................................6
5. COMMANDS...............................................................................................................7
5.1. Display/keypad commands............................................................................7
5.1.1. Display mode....................................................................................7
5.1.2. Command m ode ...............................................................................7
5.1.3. Selecting and scaling the analogue outputs ......................................8
5.1.4. Setting the serial line parameters......................................................9
5.1.5. Setting the output mode..................................................................11
5.1.6. Others ............................................................................................12
5.2. Serial commands .........................................................................................16
5.2.1. Analogue output commands............................................................16
5.2.2. Output via the serial bus .................................................................18
5.2.3. Operating the HMI38 via the serial bus ...........................................20
6. DATA LOGGING.......................................................................................................22
6.1. Logging using display/keypad commands.................................................23
6.1.1. Start/stop data logging in the
6.1.2. Start/stop data logging in the
CONTINUOUS mode.............................23
CATCH mode ......................................24
6.1.3. Outputting the logged data to the serial line ....................................25
6.1.4. Outputting the logged data to the display ........................................26
6.2. Logging using serial line commands (
CONTINUOUS mode) .........................27
6.2.1. Data logging ...................................................................................27
7. CALIBRATION..........................................................................................................30
7.1. Humidity calibration.....................................................................................30
7.1.1. Calibration procedure......................................................................30
7.2. Temperature calibration ..............................................................................31
7.2.1. With display/keypad comm ands:.....................................................31
7.2.2. With serial line c om m ands..............................................................32
7.3. Calibrating the analogue outputs................................................................32
8. USING THE HMI38 AS A FIELD CALIBRATOR ........................................................ 33
8.1. HMD/W60/70 and HM P140 series transmitters ........................................... 33
8.1.1. Calibrating transmitters with voltage outputs ...................................34
8.1.2. Calibrating transmitters with current outputs ...................................36
8.2. HMP230 series transmitters ........................................................................37
8.2.1. One point calibration.......................................................................38
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Operating Manual U063en-2.1
8.2.2. Two point calibration.......................................................................39
8.3. HMD/W 20/30 and HM P130Y series transmit ters ........................................40
9. MAINTENANCE........................................................................................................42
9.1. Reference measurements............................................................................42
9.2. Self-diagnostics........................................................................................... 42
9.3. Adjusting the contrast of the display..........................................................43
10. TECHNICAL DATA...................................................................................................43
10.1. Relative humidity.........................................................................................43
10.2. Temperature.................................................................................................43
10.3. Calculated quantities...................................................................................43
10.4. Data logging.................................................................................................44
10.5. Analogue outputs.........................................................................................44
10.6. Serial interface.............................................................................................44
10.7. Electronics ...................................................................................................44
10.8. Mechanics ....................................................................................................45
10.9. Electromagnetic compatibility ....................................................................46
10.9.1. Emissions.......................................................................................46
10.9.2. Immunity.........................................................................................46
11. ACCESSORIES AND SPARE PARTS.......................................................................46
APPENDIX 1: SERIAL COMMANDS ..........................................................................47
APPENDIX 2: ERROR MESSAGES............................................................................69
APPENDIX 3: HMP35E PROBE..................................................................................75
APPENDIX 4: HMP36E PROBE..................................................................................81
APPENDIX 5: HMP37E PROBE..................................................................................87
WARRANTY.....................................................................................................................93
This manual is valid for programme version 2.01.
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U063en-2.1 Operating Manual
1. PRODUCT DESCRIPTION
The microprocessor based HMI38 Humidity Data Processor is a light, portable
instrument with an optional carrying case and built-in rechargeable battery
which make it suitable for spot checking measurements or for use as a transfer
standard.
The HMI38 is used together with Vaisala’s HMP35E, HMP36E or HMP37E
humidity and temperature probes to measure relative humidity and temperature quickly and accurately. Two probes can be connected to each HMI38. The
HMI38 also calculates dewpoint, mixing ratio, absolute humidity and wet bulb
temperature from the relative humidity and temperature it has measured.
The HMI38 has two analogue outputs (0...1V or 0...5 V) which can be selected
and scaled freely. The HMI38 also has an RS 232C and an RS 485 interface.
The HMI38 Humidity Data Processor is used through the menu-based display.
The user can choose between metric and non-metric units. Output modes are
flexible: measured or calculated quantities can be displayed or they can be
transferred to a computer or peripheral device using either RS 232C or RS 485
serial bus. Because the HMI38 units are addressable, there can be several units
on the same RS 485 line.
The HMI38 can be used as a one point field calibrator for HMP140 series and
HMD/W60/70 transmitters with standard or customized settings, as well as for
calibrating their predecessors HMD/W20/30 and HMP130Y series. It can also
be used as a one or two point calibrator for HMP230 series transmitters. The
transmitters are calibrated using an appropriate reference cable between the
HMI38 and the calibrated transmitter.
The HMI38 can also be used as a data logger. In continuous data logging, the
user selects the interval and the starting time of logging; the HMI38 can store
up to 254 readings from both probes in CONTINUOUS mode. In addition, the
HMI38 can also be used for manual data logging. The CATCH mode enables
the user to store readings manually at any given moment. In this mode, the
HMI38 can store 127 readings from both probes. The HMI38 stores the
measured relative humidity and temperature values. When the stored data is
transferred to a computer or a peripheral through the serial bus, it calculates
the other four quantities from them.
The HMI38 is powered with DC voltage, but with an AC adapter it can be
powered from the mains. HMI38 has a built-in battery and a charger.
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Operating Manual U063en-2.1
2. TO BE NOTED WHEN MEASURING HUMIDITY
It is essential in the measurement of humidity and especially in calibration that
temperature equilibrium is reached. Even a small difference in temperature
between the measured object and the sensor causes an error. If the t emperature
is +20 °C (+68 °F) and the relative humidity 50 %RH, a difference of ±1 °C
between the measured object and the sensor causes an error of ±3 %RH. When
the humidity is 90 %RH, the corresponding error is ±5.4 %RH.
The error is at its greatest when the sensor is colder or warmer than the surroundings and the humidity is high. A temperature difference of a few degrees
can cause water to condense on the sensor surface. In an unventilated space
evaporation may take hours; good ventilation accelerates evaporation. The
HUMICAP® sensor starts to function normally as soon as the water has evapo-
rated. If the condensed water is contaminated, the life span of the sensor may
shorten and calibration may change.
10
9
8
7
6
5
4
dRH (%RH)
3
2
1
0
-40 -20 0 20 40 60 80 100
Temperature (°C)
Figure 2.1 Measurement error at 100 % RH when the dif feren ce
between the ambient and sensor temperature i s 1 °C
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U063en-2.1 Operating Manual
3. TAKING THE HMI38 INTO USE
Please, note that when you take the HMI38 into use for the first time, both
probe locations have the factory setting for the probe type HMP35E. If this is
not the case, the HMI38 displays error message(s) after power up (see
appendix 3). Error messages can be cleared by pressing ENT button several
times. Should this happen, you must initialize the probe locations. During
initialization, the HMI38 gets information on which probe locations have
probes connected to them. Initializing is described in Chapter 4.1.
If you use the instrument as a data logger, you must enter the correct date and
time; see Chapter 6.
In order to enable the HMI38 to calculate the mixing ratio and wet bulb
temperature accurately, enter the ambient air pressure through the keypad or
serial bus. This setting is described in Chapter 5.
The HMI38 has a rechargeable battery which has not been charged in the
factory. Charge the battery overnight. You can use the instrument instantly
when you connect it to the mains for charging. To maximize the battery
lifetime, completely discharge and recharge the battery about once a month.
You can discharge the battery by leaving the HMI38 on without an AC adapter
until the low battery voltage switches the HMI38 automatically off.
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Operating Manual U063en-2.1
4. COMMISSIONING
4.1. Initializing the probe locations
You can use either keypad or serial bus commands for the initialization of the
probe locations. If you use serial commands, see Appendix 1.
If the probe type setting in the HMI38 memory is not correct, some error
messages may appear on the display after power up (see Appendix 3). You can
clear these messages by pressing ENT button one or several times. When the
humidity and temperature readings appear on the display, press CL key to
enter the command mode. The first display is the main menu:
Use arrow keys to select Init which starts to blink, and then press ENT. The
following appears with the indication of PROBE 1 blinking (in this example,
HMP35E):
Use arrow keys to select the correct type for PROBE 1 (HMP35E, HMP36E,
HMP37E, HMP35BM, HMP36BM) and press ENT. If there is no probe in
location 1, select none and press ENT. Use arrow keys to select also the type
for PROBE 2 and press ENT. The HMI38 returns to the display mode showing
the current readings.
4.2. Connecting the analogue outputs
Figure 4.1 shows the connections to the analogue output connector. See
Chapter 5.1.3 and Chapter 5.1.3.2 for selecting the quantities and for scaling
the analogue outputs.
ANALOGUE OUTPUT
0-1V/0-5V
1
2
3
4
5
6
7
8
9
AGND
CH1 OU
NC
CH2 OU
AGND
NC
NC
NC
NC
D9S
Figure 4.1 Cable connections to the analogu e outpu t connector
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U063en-2.1 Operating Manual
4.3. Connecting the RS 232C or RS 485 serial bus
Figure 4.2 shows the pin configuration of the serial line connector and the
RS 232C serial line connection of the HMI38 to a peripheral device.
DO NOT CONNECT
RS 232 C RXD
RS 232 C TXD
NC
GND
NC
NC
RS 485 HI
RS 485 LO
HMI38
SER I/O
D9P
COMPUTER (IBM AT)
1
2
3
4
5
6
7
8
9
SER I/O
2
3
4
5
6
7
8
9
1
D9S
RXD
TXD
DTR
GND
DSR
RTS
CTS
RI
DCD
DO NOT CONNECT
RS 232 C RXD
RS 232 C TXD
RS 485 HI
RS 485 LO
NC
GND
NC
NC
HMI38
SER I/O
D9P
SERIAL PRINTER
(RS 232 PANASONIC KX
1
2
3
4
5
6
7
8
9
SER I/O
2
3
4
5
6
7
8
20
22
D25P
TXD
RXD
NC
NC
DSR
GND
DCD
DTR
NC
Figure 4.2 Wiring between the HMI38 and a PC or a serial line
printer using RS 232C serial line.
Connect the serial bus between the PC and the HMI38 and switch the PC on.
Use a terminal emulation programme (e.g. Procomm Plus, Datastorm or
Windows terminal) when using a PC. The following chapter lists the factory
settings for data transfer.
NOTE
When changing the serial bus settings, switch the
instrument off and on again or give the serial line
command RESET to activate the new settings.
Refer to the manuals of the PC and the terminal emulation programme when
giving serial settings.
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Operating Manual U063en-2.1
4.4. Summary of the factory settings
The factory settings of the HMI38 are the following:
• probe initializations:
-probe 1 HMP35E
-probe 2 HMP35E
• auto power-off off
• output units metric
• pressure 1013.25 hPa (= mbar)
• analogue outputs:
-channel 1 RH1: 0...100 %RH 0...1 V
-channel 2 T1: -40...160 °C 0...1 V
• serial line:
-bauds, parity, data, stop 4800, even, 7, 1
-duplexity FDX
• address 0
• serial mode stop
• echo on
• output interval 0 s
• measurement integration time16
• filter off
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5. COMMANDS
The HMI38 incorporates a microprocessor which allows the configuration to
be set according to the user’s needs. This is done through commands, either
utilizing the menus on the front panel display or giving commands through the
serial interface. The commands can be used e.g. to choose the displayed
quantities, to select and scale the analogue outputs, to calibrate the
temperature channels as well as the analogue outputs and to set the serial
interface.
5.1. Display/keypad commands
5.1.1. Display mode
In the display mode the HMI38 outputs measured and calculated quantities on
the display. You can scroll the first line with button s and the second line
with button t. After reset the instrument shows first the programme type and
version and then goes on to the display mode.
You can scroll different quantities with arrow switches. Acknowledge each
selection by pressing ENT; this way, they appear on the display even after
power off. The display also shows error messages and alarms if they occur.
5.1.2. Command mode
Press the CL key to enter the command mode. The first display is the main
menu:
You can scroll the commands with the arrow keys. The currently active
command blinks; select the desired command with the ENT key. When a menu
is on the display, either the first command or the currently valid setting blinks.
The CL key takes the HMI38 back to the display mode.
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Operating Manual U063en-2.1
5.1.3. Selecting and scaling the analogue outputs
5.1.3.1. Selecting the output
• Select Mode in the main menu and Analog outputs in the Mode menu:
• Select Mode 1V / 5V. The current settings for channel 1 are displayed:
• If the settings are correct, press ENT.
• If you need to change the settings, press CL:
− the lower limit starts blinking
− acknowledge the lower limit with ENT or change it with the nu-
meric keys, then press ENT
− the upper limit starts blinking
− acknowledge the upper limit with ENT or change it with the nu-
meric keys, then press ENT
• When channel 1 has been set, the programme goes on to channel 2;
the procedure is the same as with channel 1.
NOTE
The hardware has two basic voltage ranges: 0...1 V and
0...5 V. When scaling analogue outputs, please note that
the relative accuracy of the output may become too low
if only a very small part of either range is used to output
a quantity with a wide measurement range.
5.1.3.2. Selecting and scaling the analogue output quantities
• Select Mode in the main menu and Analog outputs in the Mode menu:
• Select Scale. The quantity and scaling for channel 1 are displayed:
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U063en-2.1 Operating Manual
• If the settings are correct, press ENT.
• If you need to change the settings, press CL:
− the quantity (RHn, Tn, Tdn, xn, an, Twn; n = 1 or 2) starts blink-
ing; change it with the arrow keys and acknowledged with the ENT
key
− the lower limit starts blinking
− acknowledge the lower limit with ENT or give a new value using
the numeric keypad and press ENT
− the upper limit starts blinking
− acknowledge the upper limit with ENT or give a new value using
the numeric keypad and press ENT
• After channel 1 has been set the settings of channel 2 appear on the
display; follow the procedure described above for channel 1.
5.1.4. Setting the serial line parameters
5.1.4.1. Turning the serial interface echo ON/OFF
• Select More in the main menu, More in the More menu and Echo in
the second More menu.
• Use the arrow keys to select the right alternative and press ENT.
5.1.4.2. Serial bus settings
• Select Seri in the main menu; the currently valid serial int erface set-
tings are displayed:
• If the settings are correct, press ENT; the programme returns to the
display mode.
• If you need to change the settings, press CL:
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Operating Manual U063en-2.1
• Select the parameter to be changed with the arrow keys and ENT key.
− Selecting baud rate:
− Selecting parity:
− Selecting data bits:
− Selecting stop bits:
− Full duplex/half duplex:
NOTE
The serial bus settings become effective only after
power off/on or the serial line command RESET.
5.1.4.3. Setting the instrument address
Address is used when more than one instrument is connected to one serial bus;
this enables communication with one instrument at a time.
10
• Select More in the Main menu and then Addr in the More menu; the
following appears on the display:
• Change the address by entering a new value and pressing ENT.
• Pressing ENT returns the programme to the More menu.
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U063en-2.1 Operating Manual
• Pressing CL returns the programme to display mode and leaves the
address unchanged.
5.1.4.4. Selecting the output units
• Select More in the Main menu and Unit in the More menu:
• Use the arrow keys to select the right alternative and press ENT.
metric non-metric
RH %RH %RH
T °C °F
Td °C °F
ag/m3gr/ft
3
x g/kg gr/lb
Tw °C °F
5.1.5. Setting the output mode
The output modes only affect output through the serial interface: the instrument accepts all display/keypad commands irrespective of which serial output
mode it is in. The HMI38 has three serial output modes: RUN, STOP and
POLL.
In the RUN mode the instrument outputs measurements automatically through
the serial interface to a PC or a peripheral. The only command that can be
given through the serial interface is S (stop), which ends the RUN mode.
In the STOP mode serial commands are given to the instrument. Measurements can be output only by giving command SEND.
The POLL mode is used when more than one instrument is connected to the
same serial bus; a single instrument can be addressed and communicated with.
When the connection to one instrument is opened in the POLL mode, this
instrument goes into STOP mode and can then accept commands normally.
Closing the connection returns the instrument to POLL mode. In POLL mode
the instrument outputs measurements only when requested (command SEND
aa). If the user has forgotten the address of the instrument, it can be checked
using display/keypad commands.
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