RTU-81 - SCADA and Telemetry Modem for ISM frequency band with SDI-12 RS-232 and IP interface

General description

The RTU-81 is a radio modem for SCADA and telemetry applications in the ISM frequency band on 433-434 MHz. Its 10mW output power, which allows it to be used without any registration makes it ideal for connecting PLC's, RTU's or other SCADA equipment over short to medium distances.

The RTU-81 has 8 binary inputs and 8 binary outputs, which are all electrically isolated, on the basic device. With up to 16 PEM expansion modules the I/O can be extended, including also analog inputs and outputs. The 8 binary inputs of the RTU-81 itself are acting also as counters, configurable as an event counter or a time counter.

An RTU-81 can be set as a master in a small radio network which allows it to exchange I/O data with up to 8 other RTU-81 (which needs to be set as a slave).


For connections to external equipment a RS-232 serial interface is present along with a SDI-12 hardware which shares the serial interface with the RS-232 connection. This allows the direct connection of SDI-12 sensors which can be accessed over the wireless connection.

The optional application platform PicoLogo allows to build local control and alarm applications with the comfort and ease of a graphical editor.

The RTU-81 comes with a 10/100 Mbit/s Ethernet interface which is used for the configuration with the embedded web server. There is no need for a configuration software, just any web browser can be used to completely configure the device.

A number of optional features like MODBUS RTU/IP-Support or IEC60870-5-support make the RTU-81 more powerful even acting as a remote I/O unit in wired- or IP-networks. All optional features can be purchased and activated anytime, even with the device already installed.

All this comes in a single, rugged aluminium enclosure which will directly fit onto a standard DIN-rail. The wide power supply voltage of 12-24V +/- 20% makes it ideal for automation and solar powered applications.



Basic device

The RTU-81 basic device always features the following interfaces and functions:

· Serial RS-232 (or RS-422/485) interface (TxD, RxD, CTS, RTS) available on a removable terminal connector

· SDI-12 interface on a removable terminal connector (shared with the RS-232 interface)

· Expansion port interface, RJ-45, for connecting up to 16 I/O expansion modules type "PEM".


· Ethernet port 10/100 Mbit/s to configure the RTU-810 using the embedded webserver

· Wireless networks to up to 8 other RTU-81 in slave mode to distribute I/O from the slaves to the master and vice versa

MODBUS access

With the MODBUS option, the RTU-81 can be accessed by MODBUS/RTU over the serial interface or by MODBUS/IP over the Ethernet connection

IEC-60870-5-101 access

With the IEC-60870-5-101 option, the RTU-81 can be accessed by IEC-60870-5-101 over the serial interface. Access by IEC-60870-5-104 is planned.


The PicoLogo application platform allows the creation of control and alarm applications with an easy to use graphical interface. With PicoLogo, the RTU-81 can be used to completely control small processes and installations.

I/O Option

The I/O option allows the extension of the RTU-81 with Piciorgros PEM modules. Up to 16 PEM modules can be connected to a single RTU-81.