skip to Main Content

I am text block. Click edit button to change this text. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Ut elit tellus, luctus nec ullamcorper mattis, pulvinar dapibus leo.

Tech Series Data Radios have Current Loop Output (CLO)  interfaces for wireless 4-20mA Output Current Transmission.

A 4-20 mA current loop is a very common method to convey the sensor data acquired for analog sensor data transmission.
This CLO interface on the wireless link will send out 4-20mA signal that was measured miles away with the GPIO radio.
The Tech Series data radios have a myriad of IO terminal options, including CLO and GPIO.

On the GPIO radio, connect Sensors to Monitor.  The GPIO will mimic the sensor a long ways away to this modem with Current Loop Output (CLO).

The Output Current coming out of this AIO  interface has 2 4-20mA current outputs.

The output currents can be sent over to this CLO radio in two ways:
1. Another Tech Series GPIO radio has 4-20mA input in it, and it sends the level information to the CLO radio.
2. Your SCADA PLC or MODBUS software can transmit a MODBUS message to the CLO radio to output the 4-20mA current you want sent out.

Tech Series Current Loop Output CLO [C]

The Tech Series CLO version of the RV-M21 and RV-M22 series radio modems is ideal for SCADA and telemetry.
The MODBUS protocol messages can be sent into the Tech Series radio over-the-air to set CLO output current.

Here is a summary of the standard IO features.  If you need other IO features or additional IO, please contact Raveon sales personnel.

The GPIO connector on the product is a Phoenix Contact 1829387 DFK-MC type connector.

Pin # Name Direction Function Level / Specification
1 RX In Serial data Input RS232  Receive Input
2 TX  Out Serial Data Output RS232 Transmit Output
3 IO0 I IO pin 0 Digital input w/pull-up resistor.
4 CO2 O Analog Output  L(4-20mA), or V (Voltage Output)
5 CO1 O Analog Output L(4-20mA), or V (Voltage Output)
6 GND Ground Connect to earth ground.

An RS232 serial data cable can be connected to pins 1, 2, and 6 to configure the internal radio modem and the MIMIC mode features.
See the RV-M21 user manual for information on how to wire an RS232 DB9 connector to the GPIO connector.
You can contact Raveon to have the device pre-configured when it is purchased, so that the RS232 serial IO pins  are not required to be use.


From the DC input power that powers the RV-M2x Tech Series Data Radio modem, the 4-20mA output current is driven. So use a good quality power supply to drive this
The ground (GND) of the enclosure is metal, and is connected to the DC input GND, and the output 4-20mA signal sent to Your Device loops the current back to the GND of this product.


Two Different Versions of the Tech Series Data Radio Modems:

RV-M21    Can run up to 5 watts RF output. This RV-M21 high-power radio is super long-range. VHF and UHF bands.

RV-M22   The M22 is miniature version with, lower-cost, lower power, and a small RF modem inside.  ISM spread spectrum version, and 2-watt VHF and UHF versions. More Info RV-M22

Both Tech Series data radio versions (M21 and M22) have the GPIO interface and the CLO interface. Use whatever RF frequency band you want. The RV-M22 is available in license free 915MHz ISM band.


The CLO Tech Series data radio modem can be configured into the MIMIC mode. MIMIC mode lets two data radios mimic each other.
One is a Master, with inputs that are sent over the air to the Slave. The Slave outputs the 4-20mA current value that was sends from the Master.

MIMIC as a great way to remotely monitor as sensor over a long distance (up to many miles). Using this wireless data connection being MIMICed is easy to remotely monitor. The Master Tech Series data radio with the GPIO interface can get the 4-20mA output from a Sensors to Monitor.
The Master radio will mimic this 4-20mA current over to the Tech Series data radio modem with the Current Look Output radio (CLO) interface front panel which outputs that same 4-20mA signal.

Raveon’s Application AN230(ModbusMx) document describes in detail how Raveon’s Tech Series products can handle MODBUS type messages.

These4-20mA SCADA features within Raveon’s wireless modems have many features and advantages:

  1. Security. Over-the-air data communication can be encrypted with AES. Each radio modem can have encryption enabled, so no 3rd party can access the wireless system.
  2. 4-20mA IoT Connection.  Your sensor can me many miles away, and this wireless CLO radio output sends the 4-20mA signal to your network device. Or you cant also take the raw data from over-the-air.
  3. Radio IDs. All Raveon data radio modems have a 16 bit ID code in them and address mask.  IDs can be used to ensure which radio talks to which radio, or to setup radios in groups. A listen address is also included in each radio so broadcasts to specific groups is easy.
  4. Repeater. All Raveon data radio modems have a store-forward option, that can be configured by ID and groups of IDs so a radio modem can be used to store and forward messages.
  5. GPS location. All Raveon data radio modems have a GPS option for location and can be configured to periodically report their location and status.
  6. TDMA. All Raveon data radio modems have a GPS option for location and TDMA timing.  If fast updates are needed, TDMA slot timing is very efficient and ensure no RF interference.

Watchdog. All Raveon product incorporate a hardware watchdog timer, to fully reset the product in case some electrical or firmware problem exists. The makes remote systems very reliable.

A SCADA master controller can connect to an RV-M21 or RV-M22  data radio modem, to send messages over the air to another RV-M21 modem with the GPIO interface, so the Master can read inputs or control outputs.

Back To Top