The RTU-81 is a radio modem designed for SCADA and telemetry applications in the license-free ISM band at 433–434 MHz. With its 10 mW output power, the RTU-81 requires no regulatory approval and is an ideal solution for connecting to PLCs, RTUs, and other SCADA systems over short to medium distances.

The RTU-81 comes equipped with 8 galvanically isolated binary inputs and 8 binary outputs as standard. These inputs and outputs can be expanded with up to 16 extension modules, which may also include analog inputs and outputs. The 8 binary inputs of the RTU-81 can function as counters and can be configured as either event counters or time counters.

In a small network, the user can configure the RTU-81 as a master, allowing it to exchange input and output data with up to 8 other RTU-81 slave units.

For connecting external devices, the user can utilize the serial RS-232 interface or the SDI-12 hardware, which shares the serial interface of the RS-232 port. This enables direct connection of SDI-12 sensors, which can be accessed wirelessly.

The optional PicoLogo application platform allows users to create local control and alarm applications using the graphical PicoLogo editor.

The RTU-81 features a 10/100 Mbit/s Ethernet interface used for configuring the RTU-81 via its integrated web server. No configuration software is required, as users can access and configure the device using any web browser.

A variety of options, such as MODBUS RTU/IP support or IEC60870-5 support, make the RTU-81 a powerful remote control solution for networked or IP-based systems. All options can be purchased and activated at any time, even after deployment, and can be installed on devices already in active use.

The RTU-81’s housing is made of robust aluminum and is designed for DIN rail mounting. With a power supply range of 12–24 V ±20%, the RTU-81 is an ideal solution for automation and solar applications.

Options and Device Features

• The standard configuration of the RTU-81 includes the following interfaces:
   Serial Interface: Via 9-pin Sub-D connector (female), RS-232 or RS-485/422 (RS-232 is standard; RS-485/422 are hardware options)
• SDI-12 Interface: On a removable screw terminal
• Extension Module Interface: RJ-45, for connecting up to 16 additional I/O extension modules of type “PEM”
• Ethernet Port: 10/100 Mbit/s for connecting IP-based devices or configuring the RTU-81 via the internal web server
• Wireless Networks: Supports up to 8 additional RTU-81 slave units to transfer I/O data between slaves and the master, and vice versa
   

MODBUS Polls

With the MODBUS option, the RTU-81 can be polled using the MODBUS/RTU protocol via the serial interface and radio, or the MODBUS/IP protocol via the Ethernet interface.

IEC-60870-5-101/104 Polls

With the IEC-60870 option, the RTU-81 can be polled using the IEC-60870-5-101/104 protocol via the serial interface and radio, as well as the IEC-60870-5-104 protocol via the Ethernet interface.

PicoLogo

The optional PicoLogo feature enables users to create autonomous logical commands and other PLC-relevant applications.

I/O Options

The I/O option allows for the expansion of the RTU-81’s inputs and outputs using expansion modules. Up to 16 “PEM” expansion modules can be connected to a single RTU-81