AL200 ALERT2 Encoder, Modulator, and Sensor Interface
ALERT2 Ready
Improved accuracy and performance for flood warning systems
weather applications supported water applications supported energy applications supported gas flux and turbulence applications supported infrastructure applications supported soil applications supported


The AL200 is an ALERT2 encoder and modulator that supports ALERT2 and ALERT-concentration services. It meets the ALERT2 standards maintained by National Hydrologic Warning Council (NHWC) and ALERT Users Group (AUG). ALERT2 improves the accuracy and performance of flood warning systems and software, by providing you with faster data transfer, forward error correction, and a TDMA architecture.

With integrated sensor inputs, the AL200 allows you to create a minimal ALERT2 transmitter/station, decreasing the cost of a typical flood warning system. Combining the AL200 with a Campbell Scientific data logger provides enhanced sensor support, user-defined logic and control, and data logging capabilities.

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Benefits and Features

  • Easily configurable with graphical, point-and-click software
  • Integrated sensor inputs for greatly reduced station cost
  • Onboard measurement of supply voltage, clock/GPS quality
  • Event or schedule driven reports for battery, clock, tipping bucket, voltage, current, SDI-12, high/low state
  • Screw terminals for power, radio, and sensors for easy cabling
  • Easy access test features for transmission, radio power, and alignment
  • Support of encrypted ALERT2 messages; support of 250-millisecond slots


Technical Description

Channels Available and Their Functions

  • P1: Tipping Bucket / Switch Closure Count Accumulator
  • SE1: Single-ended Analog Input, millivolt or milliamp
  • C1: Digital for limited SDI-12
  • SW12: Switched power for powering sensors
  • G: Ground

ALERT2 Reporting

When used standalone, the AL200 can generate time and event driven reports for Battery, Clock Status, Tipping Bucket, Analog Input (mV or mA), Digital (SDI-12).


Power Connector Two-wire, 0.15-in. pitch removable terminal (reverse polarity protected)
Power Requirements 9 to 18 Vdc
Configuration Device Configuration Utility over USB (settable modulation levels using Device Configuration Utility)
LEDs GPS, Serial, Radio (RS-232 and CS I/O share serial activity LED.)
CS I/O Port SDC 7, 8,10, or 11 (multiplexed with on-board sensor interface)
RS-232 Port DCE
USB Port Micro-B
Temperature Range -40° to +60°C
Communication Rate
  • 1200 to 115,200 bps (RS-232 DCE Port)
  • 9600 to 57,600 bps (CS I/O Port)
Current Drain
  • 1.5 mA (@ 12 Vdc when idle)
  • 40 mA (@ 12 Vdc during GPS fix)
  • 35 mA (@12 Vdc during transmit)
Timekeeping Setting via GPS ±61 μs
Drift ±0.17 s/day (without GPS sync, 40°C temperature change)
Analog Input (SE1) Sensor Interface 0 to 5 Vdc (16-bit ADC; millivolt or 4 to 20 mA selectable)
Protocols Supported ALERT(1) and ALERT2
SMA Connector Active GPS socket (female) antenna
Test Button Test transmit and tone
Dimensions 16 x 7.7 x 2.2 cm (6.3 x 3.0 x 0.9 in.)

Sensor Interface

Channels Available Switch closure (P1), single-ended analog (SE1), limited SDI-12 (C1), switched 12 V, ground
Analog input (SE1) 0 to 5 Vdc, 16-bit Adc (millivolt or 4 to 20 mA selectable)

Radio Interface

Channels Available TX, PTT, switched battery, ground
RCFSK Modulation 100 to 1000 mV, ±50 mV (software selectable)


ALERT2 ALERT2 IND API Specification Version 2.0 (as released by the ALERT2 Technical Working Group dated June 2020)
Compliance RoHS and CE
Product Standard EN 61326-1:2013
Test Standards
  • IEC 61000-4-2, Electrostatic Discharge Immunity
  • IEC 61000-4-3, Radiated RF Immunity
  • IEC 61000-4-4, Electrical Fast Transients Immunity
  • IEC 61000-4-5, Surge Immunity
  • IEC 61000-4-6, Conducted RF Immunity
  • CIPSR 11, Class B Emission


Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.


Product Compatible Note
CR1000 (retired)
CR200X (retired)
CR216X (retired)
CR5000 (retired)
CR800 (retired)
CR850 (retired)
CR9000X (retired)

Additional Compatibility Information

The AL200 supports ALERT1 and ALERT2 protocols.

A standalone AL200 can measure:

  • Analog sensors with 0 to 5 V or 0 to 20 mA output
  • SDI-12 sensors
  • Float / contact switch sensors
  • CS451 and CS456 Pressure Transducers
  • CS475, CS476, and CS477 Radar Water-Level Sensors
  • CS460 Pressure Transducer
  • SR50A Sonic Ranging Sensor
  • CS11 AC Current Sensor


ALERT Configuration Tool v.1.1 (47.7 MB) 30-06-2016

A software utility used to configure the ALERT210. 

Case Studies

Panama Canal: Upgraded Flood Warning System
The Panama Canal was using an outdated water-level system until the Panama Canal Authorities (ACP) more
Texas: Hurricane Harvey
In February of 2015, Campbell Scientific was awarded a bid to supply the Harris more
Texas: Transitioning to ALERT2
ALERT2 is a modern communication protocol that improves upon 40 years of tradition within more

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