INSTRUCTION MANUAL AL200 ALERT2 Encoder, Modulator, and Sensor Interface 4/14 C o p y r i g h t © 2 0 1 3 - 2 0 1 4 C a m p b e l l S c i e n t i f i c , I n c .
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Table of Contents PDF viewers: These page numbers refer to the printed version of this document. Use the PDF reader bookmarks tab for links to specific sections. 1. Introduction ................................................................. 1 2. Cautionary Statements ............................................... 1 3. Initial Inspection ......................................................... 1 4. Quickstart .................................................................... 2 4.1 Stand-Alone Mode .
Table of Contents B.3 B.4 B.5 B.6 B.7 USB ................................................................................................. B-2 Power ............................................................................................... B-2 Analog Radio Interface.................................................................... B-2 Sensor I/O Interface......................................................................... B-3 GPS Input ..........................................................
AL200 ALERT2 Encoder, Modulator, and Sensor Interface 1. Introduction The AL200 is an encoder, modulator, and sensor interface designed for use both as a stand-alone device and as a peripheral to a Campbell Scientific datalogger or third party Data Collection Platform (DCP). This device uses the Automated Local Evaluation Real Time Protocol version 2 (ALERT2) and can operate as both a remote ALERT2 transmitter and as an ALERT to ALERT2 concentrator and repeater.
AL200 ALERT2 Encoder, Modulator, and Sensor Interface • • • 4. QTY 4, mounting grommets (pn 6044) QTY 4, mounting screws (pn 505) QTY 1, Micro-B USB cable (pn 27555) Quickstart There are two basic modes of operation for the AL200. For simplicity, these will be referred to as stand-alone and datalogger peripheral modes. 4.1 Stand-Alone Mode 4.1.1 Physical Setup • Attach a GPS antenna to the GPS SMA connector located on the side of the AL200.
AL200 ALERT2 Encoder, Modulator, and Sensor Interface • ALERT2 Configure settings to match your ALERT2 network. • Radio Settings Default settings will work for Campbell Scientific’s RF320 series radios. (Campbell Scientific’s RF320 series is the Ritron DTX-L series. For other radios, check with the manufacturer for the necessary radio settings.) • GPS Settings Leave all settings as defaults. • Sensor Input Settings Configure settings to enable or disable the inputs you wish to use with the AL200. 8.
AL200 ALERT2 Encoder, Modulator, and Sensor Interface 3. Under Device Type, select AL200. 4. Click the browse button next to Communication Port and select the port associated with the AL200. 5. Click OK. 6. Click Connect. 7. Specify the settings on each tab as described below. • Main Set the Operation Mode to ALERT2 on CS I/O, ALERT Concentration on RS-232. • ComPort Leave all settings as defaults. • ALERT2 Configure settings to match your ALERT2 network.
AL200 ALERT2 Encoder, Modulator, and Sensor Interface FIGURE 5-1. AL200 The AL200 includes a CS I/O port and an RS-232 port for serial communications. A USB device port is used for configuring the AL200, viewing real time sensor data, and diagnostics. An SMA female connector is provided for connecting a GPS antenna, and a removable screw terminal allows for the easy connection of an analog radio. Removable screw terminals are also used for supplying power to the AL200 and connecting sensors.
AL200 ALERT2 Encoder, Modulator, and Sensor Interface FIGURE 6-1. AL200 dimensions Configuration This device is designed to easily be configured through the graphical interface, Device Configuration Utility. When used as a stand-alone device, no programming is required. NOTE The device driver for the AL200 must be installed on your computer before you can connect to the AL200 via USB. See Appendix E, AL200 USB Driver Installation Instructions, for instructions on installing the device driver.
AL200 ALERT2 Encoder, Modulator, and Sensor Interface RS-232 Port DCE Configurable baud rates, parity, stop bits, and timeout ElA/TIA-232 and V.28/V.24 Signaling ± 15kV ESD protection Test Button The test button located in the lower left hand corner of the AL200 serves two functions. Pressing it for three to six seconds will trigger a test transmission containing the latest data available to the AL200.
AL200 ALERT2 Encoder, Modulator, and Sensor Interface Switched Voltage (SW12V) Voltage supply switched on prior to operational sensor scan Thermal fuse hold current = 900 mA @ 20°C, 630 mA @ 50°C, 450 mA @ 70°C GPS SMA Female 50 Ω input impedance Active antenna design, 3.
AL200 ALERT2 Encoder, Modulator, and Sensor Interface NOTE 3. Under Device Type, select AL200. 4. Click the browse button next to Communication Port and select the port associated with the AL200. 5. Click OK. 6. Click Connect. 7. Specify the settings on each tab as described below for the desired mode. When a value is shown in parentheses next to a setting, it is the default values that should work in most cases. Do not change these values, unless you are certain a change is required. 7.1.
AL200 ALERT2 Encoder, Modulator, and Sensor Interface packet. This makes it possible to trace the path that a packet took from its beginning to its destination. Radio Settings The default radio settings have been chosen to work well with Campbell Scientific’s RF320 series (Ritron DTX-L series) radios. If using a different type of radio, consult the manufacturer and apply the changes to the following settings.
AL200 ALERT2 Encoder, Modulator, and Sensor Interface • Set the Sensor Scan Interval – This is how often the AL200 will power up and measure attached and enabled sensors. Value is expressed in seconds. • Set the SW12 Warm Up Time – This is the amount of time in seconds that the AL200 will wait after powering up attached sensors before making a measurement. • Set the P1 Mode – Enable or disable the pulse count channel depending on whether or not it is being used.
AL200 ALERT2 Encoder, Modulator, and Sensor Interface • Set the SDI-12 Offset – (0) – This is a sensor specific value that along with the SE1 Multiplier will be used to convert the analog output of a sensor to an engineering unit. See Appendix H, Calculating Multipliers and Offsets, for how to calculate multipliers and offsets. (Note that most SDI-12 sensors do not require a multiplier or offset except to convert units of measure.
AL200 ALERT2 Encoder, Modulator, and Sensor Interface • Set the Slot Length – This is the maximum amount of time within the frame that the station can report during. It is an integer value between 500 and a maximum of the Frame Length. • Set the Slot Offset – This is the amount of time into the frame that the slot will occupy. For example, if your frame is 120,000 ms (2 minutes) and your slot offset is 60,000 ms, the slot time will begin 1 minute after the beginning of the frame.
AL200 ALERT2 Encoder, Modulator, and Sensor Interface • Set the GPS Power On Interval – (30) – This is how often the GPS receiver will be powered on and an attempt to get a GPS fix will be made. Value is expressed in minutes. • Set the GPS On Max – (5) – This is the maximum amount of time, in minutes, that the GPS receiver will be powered on without a GPS fix being obtained. Sensor Input Settings These settings have no effect in datalogger peripheral mode.
AL200 ALERT2 Encoder, Modulator, and Sensor Interface Under normal operation, the AL200 will obtain a GPS fix and measure sensors based on its configuration. When the sensors are measured and an event threshold has been exceeded, the AL200 will wait until its designated time slot and then power up the radio and transmit the data to a repeater or base receiver. • Concentrated ALERT data is retransmitted using the ALERT concentration protocol.
AL200 ALERT2 Encoder, Modulator, and Sensor Interface 10. Troubleshooting Problem Possible Causes The AL200 will not transmit eventtriggered data. • The AL200 is currently connected to Device Configuration Utility and data transmissions are being suppressed. • The event threshold is not properly set. • The AL200 is not currently measuring a level that exceeds the event threshold. • The AL200 has not obtained an initial GPS fix. The Test Button is not initiating a data transmission.
Appendix A. Glossary ALERT Automated Local Evaluation in Real Time. A communication protocol developed in the early 1970’s for the efficient reporting of real-time rainfall data over radio telemetry networks. ALERT2 Successor of the ALERT communication protocol. A layered protocol suite designed for the primary purpose of real-time and coordinated communication of data over a radio telemetry network. IND Intelligent Network Device.
Appendix A.
Appendix B. Cables and Connector Pin Descriptions B.1 CS I/O CS I/O is an interface unique to Campbell Scientific products. CS I/O uses TTL signaling. CS I/O devices are connected using a 9-pin, straight-through, male to female cable with all 9 pins connected. Use of the supplied SC12 cable (pn 16675) is recommended. TABLE B-1.
Appendix B. Cables and Connector Pin Descriptions B.3 USB The USB interface is a standard Micro-B configuration. A USB A to Micro-B cable is supplied (pn 27555). Connection to a PC requires installation of the FTDI Virtual COM Port (VCP) device driver. TABLE B-3. USB Pin Description Pin Function 1 VBUS, 5 Vdc 2 Data - 3 Data + 4 Not used, Grounded Internally 5 GND B.4 Power Input power is supplied via a 2-pin screw terminal. A mating connector is supplied (pn 7843). TABLE B-4.
Appendix B. Cables and Connector Pin Descriptions TABLE B-5. Radio Interface Pin Description Pin Function Freq. Select Frequency Select. Accommodate frequency selection during operation by grounding selected pin on radio interface. SW12V Switchable radio power supply PTT Push-to-talk. Grounded during transmission. G Ground TX Transmit audio output B.6 Sensor I/O Interface The sensor I/O interface is a 5-pin screw terminal. A mating connector is supplied (pn 28750). TABLE B-6.
Appendix B.
Appendix C. LED Indicators The GPS LED is next to the GPS antenna connection. It can be used for monitoring GPS power up and acquisition of a good satellite lock / fix. TABLE C-1. GPS LED State Descriptions State Description Off GPS module in “hibernate state” Green GPS lock acquired (will only flash momentarily before turning off) Red GPS module on, No GPS Lock (or downloading almanac/leap second information) The Serial LED is located between the RS-232 and CS I/O interfaces.
Appendix C. LED Indicators C-2 b. The GPS light remains red for up 13 minutes as the AL200 downloads leap second information from the satellite. c. The Serial LED flashes green or red indicating that the AL200 has been sent data from a datalogger, or data is being internally transferred from the sensor inputs to memory. d. The Radio LED is red briefly while the radio is powered up and allowed to warm up. If the radio is set to always on, this LED will constantly be red. e.
Appendix D. AL200 Settings Operation Mode The AL200 supports ALERT2 and ALERT-concentration processing. Each process can service one physical connection on the AL200 at a time. Those connections are the CS I/O, RS-232, and direct-sensor inputs. The CS I/O port and sensor inputs are multiplexed, so their use is mutually exclusive. • ALERT2 on CS I/O, ALERT Concentration on RS-232 In this mode, the AL200 will accept ALERT2 on the CS I/O port and ALERT packets on the RS-232 port.
Appendix D. AL200 Settings Hop Limit The maximum number of times a packet, originating from this device, will be repeated (hop) before being discarded. None (7) disables the limiting of hops. Example: if this station requires 1 repeater hop to reach the base station receiver, the hop limit should be set to a minimum of 1. Path Service Enabled Request that each device that forwards data originating from this station add its source address to the packet header.
Appendix D. AL200 Settings SE1 Mode Sets the operation mode for the SE1 terminal input. SE1 is used for measuring millivolt or milliamp input signals, like those commonly produced by a pressure transducing level sensor. SE1 ALERT2 Sensor ID The ALERT2 sensor ID that will be used to identify a SE1 general sensor report. The ID cannot be set to 0 or 8. 0 is reserved for reporting P1 input. 8 is reserved for reporting battery.
Appendix D. AL200 Settings SE1 Transmitted Last three transmitted readings for SE1 (T0, T1, T2). The list will be queried and displayed here at a regular refresh interval. While connected via Device Configuration Utility, automated reporting/transmission is disabled. Press and hold the test button for 3 to 5 seconds to force a transmission while connected.
Appendix E. AL200 USB Driver Installation Instructions When plugging the AL200 into your Windows XP or Vista PC for the first time, it may be necessary to install the FTDI Virtual COM Port (VCP) driver. This is not required when using Windows 7 or 8. Visit www.ftdichip.com/Drivers/VCP and select the appropriate file based on your computer’s operating system. Download the zip file to your PC and extract the files to a directory of your choosing.
Appendix E.
Appendix F. Updating the Operating System of the AL200 Whenever a new operating system is released for the AL200, it will be available from our website, www.campbellsci.com/downloads. Follow these steps to send the new OS to the AL200: 1. Connect a USB cable between one of your computer’s USB ports and the USB port on the AL200. 2. Open DevConfig. 3. Select the AL200 under Device Type. 4. Select the appropriate Communication Port. 5. Go to the Send OS tab. 6. Press the Start button. 7.
Appendix F.
Appendix G. List of Recommended Sensor IDs TABLE G-1. Recommended Sensor IDs ID Sensor Type 0 Rain 1 Air Temperature 2 Relative Humidity 3 Barometric Pressure 4 Wind Speed 5 Wind Direction 6 Peak Wind Speed 7 Stage 8 Battery Voltage *As recommended in the ALERT2 Application Layer Protocol Specification document, Version 1.2.
Appendix G.
Appendix H. Calculating Multipliers and Offsets Unlike ALERT which could only represent measurement values between 0 and 2047, ALERT2 has the ability to represent a much larger range of floating point numbers. It is no longer necessary to scale a reading to a unit-less number less than 2047. Instead, with ALERT2, you can transmit values in engineering units with a high degree of resolution.
Appendix H. Calculating Multipliers and Offsets Now, we can calculate pressure based on the reading we get from the sensor. For example, you measure the sensor’s output as 2543.210 mV. Pressure would be determined by: Pressure = (0.0060 • 2543.210) + (–0.074) = 15.263 psi To determine water depth, simply multiply the pressure value by the appropriate conversion factor. For fresh water this is: 1 psi = 2.308 ft. For salt water this is: 1 psi = 2.250 ft.
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