RF500M Radio Modem Revision: 8/10 C o p y r i g h t © 2 0 0 8 - 2 0 1 0 C a m p b e l l S c i e n t i f i c , I n c .
Warranty and Assistance The RF500M RADIO MODEM is warranted by Campbell Scientific, Inc. to be free from defects in materials and workmanship under normal use and service for twelve (12) months from date of shipment unless specified otherwise. Batteries have no warranty. Campbell Scientific, Inc.'s obligation under this warranty is limited to repairing or replacing (at Campbell Scientific, Inc.'s option) defective products.
RF500M Table of Contents PDF viewers note: These page numbers refer to the printed version of this document. Use the Adobe Acrobat® bookmarks tab for links to specific sections. 1. General Radiotelemetry Network ...............................1 1.1 1.2 1.3 1.4 Introduction ..............................................................................................1 Field Station..............................................................................................1 Base Station ..................
RF500M Table of Contents 4. Operation of the Radiotelemetry Network ............. 4-1 4.1 Monitoring and Collecting Data with LoggerNet .................................... 1 4.1.1 Basic Concepts ............................................................................... 1 4.1.2 Using the LoggerNet Setup Screen ................................................ 1 4.1.3 Automated Data Collection with LoggerNet.................................. 2 4.1.4 General Communication – LoggerNet Connect Screen .....
Section 1. General Radiotelemetry Network 1.1 Introduction Data retrieval from a remote site can be difficult. One method to accomplish data collection from isolated sites is through a radio telemetry (RF telemetry) network. Dataloggers can be accessed by RF telemetry, which requires no physical connection from the computer to the datalogger. The RF telemetry link reduces the number of visits to a remote site for data collection. The RF telemetry network is designed for complete computer control.
Section 1. General Radiotelemetry Network 1.3 Base Station Purpose: A base station utilizes a computer to collect data from the field station(s). Normally, all communication to the field stations originate at the base station. Data retrieval, remote programming, and system analysis can all be done from the base station. Equipment Required: • Radio • RF Base Station • Computer with LoggerNet software • Antenna and antenna cable • AC power 1.
Section 2. Radiotelemetry Network Components 2.1 RF500M Modem The RF500M is an interface between the computer and the radio when used at a base station, and an interface between the radio and the datalogger at a field station. In a repeater station, the RF500M is an interface between two other communication stations. The RF500M is an RF modem. LoggerNet will refer to the RF500M as an RFBase-TD or RFRemote-PB. 2.1.
Section 2. Radiotelemetry Network Components The light located between the Transceiver port and the RS-232 port is used primarily to indicate when the radio is transmitting and receiving by blinking red and green. The light located between the RS-232 and CS I/O ports is used primarily to indicate when data is transmitted between the datalogger and RF500M modem by blinking red and green. 2.1.1.
Section 2. Radiotelemetry Network Components The lights can also be used to verify the appropriate power up sequence of the RF500M. View the indicator lights while applying power with the power adapter or connecting the datalogger to the RF500M CS I/O Port with an SC12 cable. The sequence of the lights flashing after connection indicates the power up self-test status.
Section 2. Radiotelemetry Network Components Depending on the radio being used, the appropriate internal jumper must be selected on the RF500M circuit board. There is a set of six jumpers in series located just under the Campbell Scientific, Inc. name and circuit board version number etched on the board. When looking at the front panel with the three ports, the jumpers that need to be set are located in the back, right corner of the circuit board.
Section 2. Radiotelemetry Network Components FIGURE 2-3. RF500M Radio Jumper Expanded View 2.2.3 Digital Radio Description The RF500M is compatible with digital RS-232 radios such as the DataRadio Integra radio. The digital radios are connected to the RF500M modem with a serial cable between RS-232 ports. Use Device Configuration Utility to configure the RS-232 connection options in the RF500M to work with the digital radio. 2.3 Antennas and Cables Antennas radiate and receive the radio signals.
Section 2. Radiotelemetry Network Components An omnidirectional antenna will transmit/ receive in a full 360 degree circle. Generally, an omnidirectional antenna will be a straight cylindrical rod which is to be mounted vertically at the top of a tripod. A unidirectional antenna is designed to transmit/receive in a particular direction, or in a specified sector. There are various shapes of unidirectional antennas. The most common is the Yagi antenna.
Section 2. Radiotelemetry Network Components FIGURE 2-5. The PD46 Clamp Mount FIGURE 2-6. Type-NM (male), BNC, and Type-NF (female) Connectors TABLE 2-2.
Section 2. Radiotelemetry Network Components 2.4 Tripods, Towers, Enclosures, and Power Supplies There are several methods of mounting and housing sensors and other equipment for a station. 2.4.1 Tripods and Towers for Mounting For the different mounting requirements, Campbell Scientific offers many styles and sizes of tripods and towers.
Section 3. Assembling the Radiotelemetry Network This section provides a logical order for RF network assembly and deployment. Details of specific components in the system are described in Section 2 “Radiotelemetry Network Components.” Section 2 is cross-referenced throughout this assembly section. 3.1 Final Layout The initial locations of the base, field, and repeater stations have likely been determined already. Locate RF stations on an area map, preferably a topographic map.
Section 3. Assembling the Radiotelemetry Network To configure the RF500M, apply power to the modem, wait for the power-up sequence lights to cycle and then turn off, connect the PC to the RF500M RS232 port with a null modem cable, open Device Configuration Utility, highlight the RF500M option in the Device Type list, and click Connect. Press the green configuration button on the RF500M either before or while connected to enable the settings in Device Configuration Utility.
Section 3. Assembling the Radiotelemetry Network 4. Baud Rate – Set the baud rate for the RS-232 interface. 5. Sleep-Mode Enabled – Determine if sleep mode functionality will be enabled for RF300 series radios. In all other cases, this setting will be ignored. Once the RF500M has been configured, it is ready to be deployed. 3.2.2 Install Base Station When the RF500M is used in a base station configuration, the PC is attached to the RS-232 port with a null modem cable.
Section 3. Assembling the Radiotelemetry Network Following is the order in which a general RF field station should be installed. A repeater station is installed in the same order. 1. Tripod or tower 2. Enclosure and datalogger 3. Antenna - Orient correctly; remember direction and polarization 4. Solar Panel 5. Power Supply 6. Sensors 7. RF Modem - Configure the RF ID according to the site map 8. Radio - Make sure to connect to RF Modem, to power supply, and turn on power supply 3.
Section 3. Assembling the Radiotelemetry Network Remote” then highlight the RF remote to test. Click “Start Test” and wait for the test results. After a successful RF link test, the next step is to attempt communication with the datalogger over the RF link. From the TroubleShooter client choose the “Comm Test” client. Highlight the datalogger to test and click on the “Test” button. 3.4.
Section 3.
Section 4. Operation of the Radiotelemetry Network All field stations can be accessed and monitored from the central base site. Regular visits to the field sites are required to ensure that all sensors are in place, enclosures are dry, solar panel is clean, and that the tripod and antenna are secure. Frequency of visits to the field sites are variable depending on environmental conditions and the sensors utilized.
Section 4. Operation of the Radiotelemetry Network remotes by using the same method but highlight the RFBase-TD and select RFRemote-PB. The last device to add is a datalogger. Use the Add button or right click on the RFRemote-PB and add the appropriate datalogger. If a mistake is made, highlight the mistaken device and use the Delete button. There are several fields requiring unique settings. The LoggerNet Setup screen shows different options based on which device is selected in the network map.
Section 4. Operation of the Radiotelemetry Network FIGURE 4-2. LoggerNet Setup Screen - Schedule Tab 4.1.4 General Communication – LoggerNet Connect Screen General communications include: collect data, send and retrieve programs, monitor measurements in real time, graph real time data, etc. The LoggerNet Connect screen supports these general communication tasks. Communication can only be done after the RF communication path has been setup in the Setup screen.
Section 4. Operation of the Radiotelemetry Network FIGURE 4-3. LoggerNet Connect Screen 4.2 Datalogger Initiated Communications The datalogger can send collected data to LoggerNet using the SendData instruction in the datalogger. This method of data collection is referred to as One Way Data. With scheduled data collection disabled and LoggerNet running, the RF polling process of the RF500M retrieves data sent from the datalogger to LoggerNet.
Section 4. Operation of the Radiotelemetry Network When programming a PakBus datalogger, the SendData instruction must be included in the datalogger to enable One Way Data. When the datalogger executes this instruction and a new record exists in the specified table, the datalogger sends the record out the interface declared in the instruction. In an RF500M network, the record is sent directly to a buffer in the RF remote and the record is collected during the next RF polling procedure.
Section 4. Operation of the Radiotelemetry Network If the RF remote is storing more data in its buffer than can be sent in the defined time window of the polling event, the RF Remote requests more time to send the remaining data. After all RF remotes have had a chance to respond during their defined time windows within the polling event, the RF remote that requested additional time to send more data takes control of the RF medium and takes any additional time necessary to transmit data.
Appendix A. Fundamentals of Radiotelemetry A.1 Radio Waves Radiotelemetry is the process of transferring information (data) in the form of radio waves. The data is transferred on a carrier wave, which normally has a sinusoidal form. Therefore, the carrier wave can be described entirely by the frequency, amplitude, and phase with respect to a reference. The commonly used term for radiotelemetry, RF, refers to radio frequency, which in actuality is the frequency of the carrier wave.
Appendix A. Fundamentals of Radiotelemetry filtering efficient, and to isolate the radio waves from the common low frequency man-made noise. The main forms of modulation are amplitude, frequency, and pulse modulation. Frequency modulation (FM) is used by Campbell Scientific. A.2 Antennas An antenna is a device that captures and radiates radio waves. The antenna at the transmitting station is excited by the transmitting radio. The antenna converts energy from the radio to radiated energy.
Appendix A. Fundamentals of Radiotelemetry sequences, sets data to be transferred into data blocks, creates signatures of data blocks, modulates the radio's carrier wave, and stores information on communication quality. The user at the computer is responsible for naming the desired communication path with a setup string. This setup string contains any repeater (MOL) modem IDs and the destination (EOL) modem ID in sequence.
Appendix A.
Appendix B. Power Calculations There must be enough transmission power in any RF link to complete communication. The sources of power are the radio and the antennas. Conversely, power is lost both through the cables (coax loss) and over the distance of communication (path loss). The power of the signal received (Signal Power) can be calculated as stated below. The signal power must be greater than -95 dBm (-80 dBm @ 2.4K baud) to have a good radiotelemetry link.
Appendix B. Power Calculations Power Conversion Conversion of Watts to dBm can be done with the following formula. dBm = 10 * Log((Watts)/0.
Glossary Antenna - Device for radiating and receiving radio signals. Attenuation - The reduction of an electrical signal without appreciable distortion. Base Station - The destination for accumulated data; where data is received via radio from one or more field stations. Baud Rate - A unit of data transmission speed, normally equal to one bit per second. Block - Group of ones and zeroes which represent data or commands. BNC Connector - A commonly used "twist type" connector on radios.
Glossary Radio Frequency - The number of cycles per second with which the carrier wave travels, usually specified in Megahertz. Radiotelemetry - Process of transmitting data by radio communication. Radiotelemetry Link - A temporary communication path within a network. Radiotelemetry Network - A group of stations which communicate by radio and are used to indicate or record data. Reflected Power - Energy that is transferred back into the radio after it has been transmitted by the same radio.
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