Campbell HMP155A Product Manual
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Campbell HMP155A Product Manual

Temperature and relative humidity probe
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Revision: 10/2021
Copyright © 1990 – 2021
Campbell Scientific, Inc.

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Summary of Contents for Campbell HMP155A

  • Page 1 Revision: 10/2021 Copyright © 1990 – 2021 Campbell Scientific, Inc.

  • Page 2: Table Of Contents

    Table of contents 1. Introduction 2. Precautions 3. Initial inspection 4. QuickStart 5. Overview 6. Specifications 6.1 Temperature sensor 6.2 Relative humidity sensor 7. Installation 7.1 Wiring to data logger 7.2 Data logger programming 7.2.1 VoltSE() instruction 7.2.2 VoltDiff() instruction 7.3 Mounting 7.3.1 Installation in a 41005-5 14-plate shield 7.3.2 Installation in a RAD14 14-plate shield...
  • Page 3 10. References Appendix A. Importing Short Cut code into CRBasic Editor Appendix B. RS-485 output B.1 SDM-SIO1A or SDM-SIO4A serial I/O module interface option B.2 MD485 interface option B.2.1 MD485 multidrop interface configuration B.3 Numeric display Table of Contents - ii...

  • Page 4: Introduction

    1. Introduction The HMP155A probe monitors relative humidity (RH) for the range of 0 to 100% RH and temperature for the range of –80 to 60 °C. It provides reliable measurements for a wide range of applications as part of a weather station system or as a single instrument. All Campbell Scientific data loggers are compatible.

  • Page 5: Quickstart

    1. Open Short Cut and click Create New Program. 2. Double-click the data logger model. 3. In the Available Sensors and Devices box, type HMP155A or locate the sensor in the Sensors > Meteorological > Relative Humidity & Temperature > HMP155 Temperature and Relative Humidity Sensor folder.
  • Page 6 6. In Output Setup, type the scan rate, meaningful table names, and Data Output Storage Interval. NOTE: The HMP155A has a five second settling time after power up; therefore the scan rate must be greater than five seconds when using the panel switched power option. HMP155A Temperature and Relative Humidity Probe...

  • Page 7: Overview

    (PRT) and a Vaisala HUMICAP 180 capacitive relative humidity sensor. The HMP155A outputs a 0 to 1 VDC signal for temperature and relative humidity that can be measured by all models of Campbell Scientific data loggers with model HMP155ACBL1 cable. The HMP155A also has RS-485 outputs for temperature and relative humidity that can be directly interfaced to the CR6 and CR1000X data logger using the HMP155ACBL2 cable.

  • Page 8: Specifications

    HMP155A. Current Campbell Scientific data loggers have a built-in switched 12 VDC that can be used to control power. NOTE: HMP155A sensors purchased directly from Vaisala with serial numbers < E4430001 require approximately 5 seconds warm up time.
  • Page 9 8-Pin Connector FIGURE 6-2. Wiring of HMP155A 8-pin connector *HMP155ACBL1 Cable provided by Campbell Scientific 1 = V 1 (yellow, temp) 2 = no connection 3 = A (white) 4 = V 2 (blue, RH) 5 = no connection 6 = no connection...

  • Page 10: Temperature Sensor

    ±(0.055 + 0.0057 x temperature) °C See the following graph: Temperature sensor: Pt 100 RTD 1/3 Class B IEC 751 Response time (63 %) for additional temperature probe in 3 m/s air flow: 63% <20 s 90% <35 s HMP155A Temperature and Relative Humidity Probe...

  • Page 11: Relative Humidity Sensor

    (p. 2) for a Short Cut tutorial. 7.1 Wiring to data logger The HMP155A probe can be measured with two single-ended or differential analog input channels. Differential measurements are recommended for cable lengths greater than 6.1 m (20 ft). See Long cable lengths (p.
  • Page 12 U terminals are automatically configured by the measurement instruction. CAUTION: When measuring the HMP155A with single-ended measurements, the white and black wires must both be connected to ⏚. Doing otherwise will connect the data logger analog and power ground planes to each other, which in some cases can cause offsets on low-level analog measurements.

  • Page 13: Data Logger Programming

    U terminals are automatically configured by the measurement instruction. 7.2 Data logger programming Short Cut is the best source for up-to-date programming code for Campbell Scientific data loggers. If your data acquisition requirements are simple, you can probably create and maintain a data logger program exclusively with Short Cut.

  • Page 14: Voltdiff() Instruction

    When cable lengths are longer than 6.1 meters or when the sensor is constantly powered, the VoltDiff() measurement instruction is used to measure the HMP155A sensor. The HMP155A output scale is 0 to 1000 millivolts for the temperature range of -80 to 60 °C and for the relative humidity range of 0 to 100%.
  • Page 15 Adjustable wrench with a minimum 1-7/8 inch jaw size To install the HMP155A, you will need the 41005-5 or RAD14 14-Plate Radiation Shield. The HMP155A is packaged with a white connector cover and a yellow sensor head protective cap. See FIGURE 7-1 (p.

  • Page 16: Installation In A 41005-5 14-Plate Shield

    3. Hold the collar and sensor, and finish threading the collar into the shield by hand. Tighten the hex plug so it compresses against the body of the HMP155A to hold it inside the 41005-5 radiation shield. Use an adjustable wrench if necessary, but do not overtighten the collar.

  • Page 17: Installation In A Rad14 14-Plate Shield

    1. Loosen the nut on the entry gland at the bottom of the shield. 2. Remove the yellow protective cap on the HMP155A, and insert the sensor into the shield. 3. Insert the sensor up into the gland as far as it will go. See FIGURE 7-5 (p.

  • Page 18: Operation

    Understanding the details in this section is not required for the general operation of the HMP155A with Campbell Scientific data loggers. The signal reference (white) and the power ground (black) are connected inside the HMP155A. When the HMP155A temperature and relative humidity are measured using a single-ended...

  • Page 19: Absolute Humidity

    12 V. The voltage will drop along those wires because thewires have resistance. The HMP155A draws approximately 4 mA when it is powered. The wire used in the HMP155A has resistance of 27.7 Ω/1000 ft. Since the signal reference and the power ground are both connected to ground at the data logger, the effective resistance of those wires together is half of 27.7 Ω/1000 ft, or 13.9 Ω/1000 ft.

  • Page 20: Troubleshooting And Maintenance

    (p. 10)). 9.2 Maintenance The HMP155A probe requires minimal maintenance. Check monthly to make sure the radiation shield is free from debris. The white screen at the tip of the probe should also be checked for contaminates. HMP155A Temperature and Relative Humidity Probe...

  • Page 21: Cleaning

    Recalibrate the HMP155A annually. Refer to the Assistance page at the back of this document for the procedure for returning the HMP155A to the factory to get recalibrated. 9.2.1 Cleaning Clean the probe with a soft, lint-free cloth moistened with mild detergent.

  • Page 22: References

    Table 9-1 (p. 19) lists the maximum ® ambient concentrations, of some chemicals, that the HUMICAP can be exposed to. Table 9-1: Chemical tolerances of HMP155A Chemical Concentration (PPM) Organic solvents 1000 to 10,000 Aggressive chemicals 1 to 10 (e.g., SO...
  • Page 23 Meyer, S. J. and K. G. Hubbard, 1992: Nonfederal Automated Weather Stations and Networks in the United States and Canada: A Preliminary Survey, Bulletin Am. Meteor. Soc., 73, No. 4, 449-457. Vaisala, Inc. (2008) HMP155A Humidity and Temperature Probe User Guide, Helsinki, Finland. Text and figures used with permission of Vaisala, Inc.

  • Page 24: Appendix A. Importing Short Cut Code Into Crbasic Editor

    Block. This adds an apostrophe (') to the beginning of each of the highlighted lines, which instructs the data logger compiler to ignore those lines when compiling. The Comment Block feature is demonstrated at about 5:10 in the CRBasic | Features video HMP155A Temperature and Relative Humidity Probe...

  • Page 25: Appendix B. Rs-485 Output

    Appendix B. RS-485 output The HMP155A outputs a 0 to 1 VDC signal for temperature and relative humidity that can be measured by all models of Campbell Scientific data loggers with model HMP155ACBL1 cable. The HMP155A also has RS-485 outputs for temperature and relative humidity that can be interfaced to the CR6 or CR1000X data loggers with model HMP155ACBL2 cable.

  • Page 26: Md485 Interface Option

    CS I/O port. Connect the MD485 CS I/O port to the data logger CS I/O port with an SC12 cable. The HMP155A has a default RS-485 baud rate of 4800, which must be changed to 9600 to be compatible with the MD485. To change settings in the HMP155A, Vaisala USB to RS-485 cable is required to interface the HMP155A sensor to a computer.
  • Page 27 Insert the CD into the computer CD drive and follow the prompts. Use the Device Manager in Windows to determine which COM port the USB/RS-485 cable was assigned: HMP155A Temperature and Relative Humidity Probe...
  • Page 28 Configure Windows HyperTerminal for the appropriate COM port (for example, COM8 in the example above) for the default HMP155A RS-485 settings of 4800 baud, 7, E, 1. Using HyperTerminal, send the following commands to the HMP155A: VERS[enter] to get a response from the sensor; for example, HMP155A 1.26 SERI[enter] to get the current RS-485 settings;...
  • Page 29 The following shows the responses to the commands. After changing the settings, change the baud rate in HyperTerminal to 9600, and make sure the relative humidity and temperature string is being displayed before connecting the sensor to the MD485. HMP155A Temperature and Relative Humidity Probe...

  • Page 30: Md485 Multidrop Interface Configuration

    2. Type MD485 in the Device Type box and click MD485. 3. Connect the MD485 to power. 4. Connect the MD485 RS-232 port to a computer serial port. 5. Select the Communication Port in the left panel. 6. Click Connect. HMP155A Temperature and Relative Humidity Probe...
  • Page 31 7. Select CS I/O and RS-485 for the Active Ports and Transparent Communication as the Protocol Configuration. 8. Click the CS I/O tab and select SDC Address 7 for the CS I/O Mode. HMP155A Temperature and Relative Humidity Probe...

  • Page 32: Numeric Display

    10. Connect the MD485 CS I/O port to the data logger CS I/O port using an SC12 cable. 11. Use the HMP155ACBL2 to connect the HMP155A sensor to the MD485 and the data logger as shown in the following table. The table also shows wiring for cables purchased from Vaisala.
  • Page 33 Type ‘W’ for the Serial Comms Sniffer. Type 32 for the SDM-SIO1A/SIO4A or 4 for the MD485, then type Y for ASCII. Raw serial data received by the buffer is displayed on the screen. HMP155A Temperature and Relative Humidity Probe...
  • Page 34 HMP155A Temperature and Relative Humidity Probe...
  • Page 35 See Product Details on the Ordering Information pages at www.campbellsci.com . Other manufacturer's products, that are resold by Campbell Scientific, are warranted only to the limits extended by the original manufacturer. Refer to www.campbellsci.com/terms#warranty for more information.
  • Page 36 To obtain a Returned Materials Authorization or Repair Reference number, contact your CAMPBELL SCIENTIFIC regional office. Please write the issued number clearly on the outside of the shipping container and ship as directed. For all returns, the customer must provide a “Statement of Product Cleanliness and Decontamination”...
  • Page 37 Do not recharge, disassemble, heat above 100 °C (212 °F), solder directly to the cell, incinerate, or expose contents to water. Dispose of spent batteries properly. WHILE EVERY ATTEMPT IS MADE TO EMBODY THE HIGHEST DEGREE OF SAFETY IN ALL CAMPBELL SCIENTIFIC PRODUCTS, THE CUSTOMER ASSUMES ALL RISK FROM ANY INJURY RESULTING FROM IMPROPER INSTALLATION, USE, OR MAINTENANCE OF TRIPODS, TOWERS, OR...
  • Page 38 Campbell Scientific Regional Offices Australia France Thailand Location: Garbutt, QLD Australia Location: Vincennes, France Location: Bangkok, Thailand Phone: 61.7.4401.7700 Phone: 0033.0.1.56.45.15.20 Phone: 66.2.719.3399 Email: info@campbellsci.com.au Email: info@campbellsci.fr Email: info@campbellsci.asia Website: www.campbellsci.com.au Website: www.campbellsci.fr Website: www.campbellsci.asia Brazil Germany Location: São Paulo, SP Brazil...

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