General
Serial interface types	RS-232/422/485
Maximum number of TCP slaves in RTU/ASCII master	32

The Moxa MB3280/EU is a Device-Server of the MGate MB3000 series, specifically designed as a Modbus Gateway for bidirectional conversion between Modbus TCP and the serial protocols Modbus RTU and Modbus ASCII. It enables integration of existing serial Modbus devices into modern Ethernet-based networks and also allows serial Modbus masters to access TCP-based Modbus slaves. The MB3000 device family is designed for flexible and scalable network configurations, with the MB3280/EU being particularly suitable for applications with high node density.

Applications

The MB3280/EU is used in industrial automation systems where a bridge between older serial control devices and modern Ethernet networks is required. Typical application scenarios include networking sensors, actuators, frequency converters, or PLCs connected via RS-232/422/485 with an upper-level Modbus TCP network. The devices are designed for use in factories, power supply facilities, building technology, and other industrial environments where reliable and maintenance-friendly communication is required.

Functions and Features in Detail

The MB3280/EU features two serial ports, each independently configurable for RS-232, RS-422, or RS-485. Each port can be individually operated for Modbus RTU or Modbus ASCII, with different baud rates configurable per port. This allows simultaneous connection of various serial Modbus devices with different communication parameters to a single Modbus TCP network. The maximum number of supported serial slaves is 31 per port, enabling a total of 62 slaves. Simultaneously, up to 16 Modbus TCP masters can access the serial slaves.

Technology Explained Simply

The operation is based on protocol conversion: A Modbus TCP master sends a request over the Ethernet network to the MB3280/EU. The device translates the request into Modbus RTU/ASCII format and forwards it via the corresponding serial port to the connected slave. The slave’s response is then converted back to Modbus TCP and sent back to the original master. This bidirectional conversion occurs in real time and enables seamless integration without changing existing device configurations. The devices are also designed to function as Modbus RTU/ASCII masters, allowing up to 32 TCP slaves to be addressed.

Compatibility and Accessories

The MB3280/EU is compatible with all devices supporting Modbus RTU or Modbus ASCII over RS-232/422/485, as well as with Modbus TCP networks. Configuration is performed via a web interface or a serial console, with detailed instructions provided in the technical documentation. The MB3000 device family also includes models MB3180 and MB3480, which offer different port configurations and capacities. For example, the MB3480 supports up to 124 serial slaves, making it suitable for even larger networks.

Mounting and Installation

Installation is carried out via a standard Ethernet connection (RJ45) and serial connections (DB9 or similar sockets). The devices are intended for use in 19-inch racks or on control panels. Configuration is performed via a web interface accessible through a standard web browser. Settings include selection of serial interfaces, protocol type (RTU/ASCII), baud rate, data bits, parity, and stop bits. The devices are designed for industrial environments, with exact protection rating and operating voltage specified in the technical data.

Advantages in Operation

The MB3280/EU enables cost-effective and reliable integration of Modbus serial communication into Ethernet networks. Support for up to 16 simultaneous TCP masters and 62 serial slaves offers high scalability. Individual configuration of the serial ports allows connection of heterogeneous devices without requiring additional gateways. The bidirectional functionality as master and slave significantly expands application possibilities. The devices are designed for maintenance-friendly and stable operation in industrial applications.