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 U063en-2.1 HMI38 Operating Manual Contents 1. 2. 3. 4. PRODUCT DESCRIPTION.......................................................................................... 1 TO BE NOTED WHEN MEASURING HUMIDITY ........................................................ 2 TAKING THE HMI38 INTO USE.................................................................................. 3 COMMISSIONING....................................................................................................... 4 4.1. 4.2. 4.3. 4.4. 5. Initializing the probe locations...................................................................... 4 Connecting the analogue outputs................................................................. 4 Connecting the RS 232C or RS 485 serial bus ............................................. 5 Summary of the factory settings ................................................................... 6 COMMANDS ............................................................................................................... 7 5.1. Display/keypad commands............................................................................ 7 5.1.1. Display mode .................................................................................... 7 5.1.2. Command mode ............................................................................... 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 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 5.2. 6. DATA LOGGING....................................................................................................... 22 6.1. Logging 6.1.1. 6.1.2. 6.1.3. 6.1.4. using display/keypad commands ................................................. 23 Start/stop data logging in the CONTINUOUS mode ............................. 23 Start/stop data logging in the CATCH mode ...................................... 24 Outputting the logged data to the serial line .................................... 25 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. 7.2. Humidity calibration..................................................................................... 30 7.1.1. Calibration procedure...................................................................... 30 Temperature calibration .............................................................................. 31 7.2.1. With display/keypad commands: ..................................................... 31 7.2.2. With serial line commands .............................................................. 32 Calibrating the analogue outputs................................................................ 32 7.3. 8. USING THE HMI38 AS A FIELD CALIBRATOR........................................................ 33 8.1. HMD/W60/70 and HMP140 series transmitters ........................................... 33 8.1.1. Calibrating transmitters with voltage outputs ................................... 34 8.1.2. Calibrating transmitters with current outputs ................................... 36 HMP230 series transmitters ........................................................................ 37 8.2.1. One point calibration ....................................................................... 38 i 8.2. HMI38 Operating Manual U063en-2.1 8.2.2. 8.3. 9. Two point calibration ....................................................................... 39 HMD/W 20/30 and HMP130Y series transmitters ........................................ 40 MAINTENANCE ........................................................................................................ 42 9.1. 9.2. 9.3. Reference measurements ............................................................................ 42 Self-diagnostics ........................................................................................... 42 Adjusting the contrast of the display.......................................................... 43 10. TECHNICAL DATA ................................................................................................... 43 10.1. 10.2. 10.3. 10.4. 10.5. 10.6. 10.7. 10.8. 10.9. Relative humidity ......................................................................................... 43 Temperature ................................................................................................. 43 Calculated quantities ................................................................................... 43 Data logging ................................................................................................. 44 Analogue outputs......................................................................................... 44 Serial interface ............................................................................................. 44 Electronics ................................................................................................... 44 Mechanics .................................................................................................... 45 Electromagnetic compatibility .................................................................... 46 10.9.1. Emissions ....................................................................................... 46 10.9.2. Immunity......................................................................................... 46 11. ACCESSORIES AND SPARE PARTS ....................................................................... 46 APPENDIX 1: APPENDIX 2: APPENDIX 3: APPENDIX 4: APPENDIX 5: SERIAL COMMANDS .......................................................................... 47 ERROR MESSAGES ............................................................................ 69 HMP35E PROBE.................................................................................. 75 HMP36E PROBE.................................................................................. 81 HMP37E PROBE.................................................................................. 87 WARRANTY ..................................................................................................................... 93 This manual is valid for programme version 2.01. ii U063en-2.1 HMI38 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. 1 HMI38 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 temperature 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 evaporated. If the condensed water is contaminated, the life span of the sensor may shorten and calibration may change. 10 9 8 7 dRH (%RH) 6 5 4 3 2 1 0 -40 -20 0 20 40 60 80 100 Temperature (°C) Figure 2.1 Measurement error at 100 %RH when the difference between the ambient and sensor temperature is 1 °C 2 U063en-2.1 HMI38 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. 3 HMI38 Operating Manual U063en-2.1 4. 4.1. COMMISSIONING 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). ...