UHF / VHF Radios / RF500M
RF500M Radio Modem
Versatile Radio Modem
For networks with narrowband, UHF/VHF, licensed radios
weather applications water applications energy applications gas flux & turbulence applications infrastructure applications soil applications


The RF500M is a versatile radio modem for networks with UHF/VHF radios, typically serving as an interface between the datalogger and radio. In addition to serving as a field modem connected to a datalogger, the RF500M can also be used as a stand-alone repeater, or as a base-station modem connected to a computer. The RF500M is generally used with legacy or existing PakBus and mixed-array/dial-up networks. The RF500M works with our RF320-series radios, RF310-series radios, RF300-series radios, or any radio and modem combination that outputs a demodulated byte stream via RS-232.

For new installations, please consider one of our spread-spectrum radio solutions, or contact Campbell Scientific to discuss the use of other licensed radio options such as the Teledesign TS4000

The RF500M is an appropriate choice for any ALERT(1) store-and-forward repeaters or base-station-decoder applications. For ALERT2 applications, refer to the ALERT200 ALERT2 Basic Remote Data Platform.

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Benefits and Features

  • Supports multiple radio configurations
  • Uses software (i.e., DevConfig) instead of hardware modifications to upgrade the operating system (OS) and change RF ID or other settings
  • Provides an RS-232 port (DTE) for modem configuration or attachment of an RS-232 radio
  • Avoids all collisions within a network, thus increasing polling speeds and reducing overall current drain


Detailed Description

The RF500M serves as a remote, repeater, and base station communication interface, generally for our licensed radio applications. It provides an interface between a datalogger or computer and a radio and can be a stand-alone repeater when onsite logging is not required. The RF500M is powered from the CS I/O port or from an external power connection. This modem is software configurable, and has been designed to interface with data telemetry radios such as our RF320-, RF310-, and RF300-series VHF/UHF radios.

-PB Operating System

The RF500M's -PB operating system was designed to quickly and efficiently move data through a network, making it a perfect choice for large networks or networks requiring fast collection intervals.

The time division polling (TD-RF) nature of the network provides collision free communications as the base modem controls when and how all data moves. An area wide poll releases station-originated data, with each station having its own dynamically allocated slot in which to transmit. The data is collected and moved through the network back to the base. Two-way communications allow each station to be remotely administered (send program, change variables, etc.) from the base. Station-to-station communications are possible using PakBus; however communications occur on the poll and must be routed though the LoggerNet server.

-DA Operating System

The -DA operating system enables each station to be dialed from anywhere in the network, at any time. This ability supports masterless point-to-point communications.

-AL Operating System

The ALERT (Automated Local Evaluation in Real Time) operating system (OS) allows for transmission, repeating, and reception of binary ALERT formatted data. Additionally, it is a derivative of the -PB OS, and therefore supports both ALERT and TDRF communications (allowing true two-way communication with a station). For ALERT2 systems, please refer to the ALERT200.

When used as an ALERT transmitter, the RF500M accepts an array of ALERT ID/Value pairs allowing multipacket transmissions. It can also turn any station into a store-and-forward ALERT repeater with programmable pass/reject lists. With the ability to transmit, receive, decode, and repeat ALERT data, the RF500M and datalogger allow for the creation of standard and advanced ALERT network components including:

  • Transmitters
  • Repeaters with sensor inputs
  • Store-and-forward repeaters
  • Multifrequncy repeaters
  • Data concentrators
  • Robust high traffic base stations


Voltage 7 to 20 Vdc (Can be provided by the CS I/O port.)
Active Current Drain < 8 mA RMS (@ 12 Vdc)
Temperature Response -25° to +50°C (standard)
Temperature Range -55° to +85°C (extended)
Dimensions 16.0 x 9.5 x 2.2 cm (6.31 x 3.69 x 0.88 in.)
Weight 0.18 kg (0.4 lb)


Datalogger Considerations

Time division polling and PakBus communications can be used in the same network as long as all of the dataloggers are PakBus versions.

Compatible Contemporary Dataloggers

RF500M OS CR200(X) Series CR800/
CR1000 CR3000 CR6 CR9000X CR300 Series
-PB # ** #

Compatible Retired Dataloggers

21X CR

#The RF500M cannot be a repeater while the modem is connected to a CR200(X) or CR300-series datalogger.
**The RF500M is only compatible with the CR6 when using -PB OS version 3 or later.
The -PB OS option for the RF500M is only compatible with the -PB and -TD OS for the CR510, CR10X, and CR23X.
The -DA OS option for the RF500M is NOT compatible with the -TD OS option for the CR510, CR10X, and CR23X.


Three jumper settings allow the RF500M to be used with a variety of radios. Though not a requirement, it is a good idea to standardize your network to use a single radio type. This practice simplifies operations and maintenance and provides the highest degree of interstation compatibility possible.

RF320 Series RF310 Series RF300 Series Calamp
RS-232 Radio
RF200 RF100

The RF500M must have the -PB OS option to use a digital RS-232 radio with it.

Radio Modems and Radio Base Stations

Networks can contain a mixture of RF500M modems and other Campbell Scientific radio modems and base stations assuming they have compatible operating systems (see chart below).

Base Station
RF500M -PB *
RF500B -PB *
RF310M -TD *
RF310B -TD *
RF315M -TD *
RF95A -TD *
RF232A -TD *

 When taking advantage of TDRF and two-way communication.


RF500M ALERT OS v.02 (770 KB) 01-04-2012

Execution of this download copies the ALERT Operating System (-AL) for the RF500M onto your computer. The ALERT (Automated Local Evaluation in Real Time) OS allows for transmission, repeating, and reception of binary ALERT formatted data. This OS is compatible with the CR200(X) series, CR800 series, CR1000, and CR3000.

Note: Requires Device Configuration Utility 2.01 or newer.

View Update History

RF500M DIAL OS v.01 (714 KB) 02-27-2012

Execution of this download copies the Dial Operating System (-DA) for
the RF500M onto your computer. The dial OS works with both mixed-array
and PakBus/Table based loggers with the exception of the CR200(X);
only the CS I/O port of the modem is used for data transfer. Each
station can be a point-to-point node and repeater and can be dialed by
LoggerNet for data transfer and remote administration.

Note: Requires Device Configuration Utility 2.01 or newer.

RF500M OS v.04 (492 KB) 02-04-2016

Execution of this download copies the PakBus Operating System (-PB) for the RF500M onto your computer. The -PB OS uses TD-RF polling to quickly and efficiently move data through a network. Additionally, each station can be individually dialed by LoggerNet. This OS is compatible with -TD, -PB, and our current generation of PakBus dataloggers.

Note: Requires Device Configuration Utility 2.01 or newer.

View Update History

Frequently Asked Questions

Number of FAQs related to RF500M: 7

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  1. 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.
  2. Usually, yes. Contact Campbell Scientific for a returned material authorization number (RMA) and instructions for returning the unit for repair. Additional information is available on the Repair and Calibration page.

  3. Yes. When the RF500M is powered up (or whenever the internal processor is reset), each of the LED indicators on the modem will illuminate, cycle through a series of colors, and turn off. This is an indication that the RF500M is running the Power On Self-Test (POST). If the LEDs remain illuminated, this is an indication that the POST has failed.
  4. No. The RF500M cannot be directly interfaced with a GPS receiver. However, most Campbell Scientific dataloggers can be interfaced with the output from a GPS receiver and programmed to extract the positional information. This information can then be accessed via an RF500M/RF320 RF link.
  5. Engineering drawings, in general, are not made accessible to the public. For a specific question, contact Campbell Scientific for assistance.

  6. No. The CR1000KD is designed specifically for use on the CS I/O port of the CR800, CR1000, and CR6 dataloggers. 

  7. If the RF modem has a CS I/O connector, then it should be compatible with the CR10X without the use of an SC932A. Ensure that the RF modem’s firmware is compatible with the CR10X firmware.

    Note: RF modems that are not sold by Campbell Scientific will only interface with a CR10X via an SC932A or an SC105. 

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