MOXA MGate MB3270

Overview

MOXA MGate MB3270 is a 2-port advanced serial-to-Ethernet Modbus gateway from the Moxa MGate MB3170/MB3270 series. It converts between Modbus TCP, Modbus ASCII and Modbus RTU protocols, enabling Ethernet masters to control serial slaves and serial masters to control Ethernet slaves. The gateway supports serial-to-Ethernet communication as well as serial-master to serial-slave communication, and allows serial and Ethernet masters to access serial Modbus devices at the same time. It is designed for industrial edge connectivity, SCADA integration and legacy serial equipment connected to Ethernet control networks. The MB3270 series is listed as NRND, not recommended for new design, and is still widely traded as an industrial MRO spare for existing Moxa Modbus gateway installations.

Features

MOXA MGate MB3270 provides two serial ports, each software-selectable for RS-232, RS-422 or RS-485, with DB9 male connectors. The Ethernet interface includes two 10/100BaseTX RJ45 ports supporting built-in Ethernet cascading, with Auto MDI/MDI-X connection and 1.5 kV magnetic isolation protection. Up to 32 Modbus TCP clients or masters can access the gateway, and up to 32 Modbus TCP servers or slaves can be connected; on the serial side, the MB3270 supports Modbus RTU/ASCII slave devices. Auto Device Routing simplifies large Modbus installations by automatically building the slave ID routing table, and routing can be controlled by IP address, TCP port number or ID mapping.

The gateway includes a priority control function that lets urgent commands receive an immediate response, along with emergency request tunnels for QoS control and embedded Modbus traffic monitoring to ease troubleshooting. Configuration is available through the web console over HTTP/HTTPS, the Device Search Utility, MGate Manager, MCC tool or Telnet console. Management supports ARP, DHCP client, DNS, HTTP, HTTPS, SMTP, SNMPv1/v2c/v3, SNMP trap, TCP/IP, Telnet, UDP and NTP client. Security includes local database authentication, HTTPS TLS 1.2, AES-128, AES-256 and SHA-256 encryption, and SNMPv3. The MB3270I isolation variant offers 2 kV serial isolation protection. Standard and wide-temperature models are available, with redundant dual DC power inputs and one relay output.

Specs

Product series: Moxa MGate MB3170/MB3270 Modbus gateway Model: MOXA MGate MB3270 Type: 2-port serial-to-Ethernet Modbus gateway Serial ports: 2 x DB9 male, RS-232/422/485 software selectable Serial baudrate: 50 bps to 921.6 kbps Data bits: 7, 8 Parity: None, Even, Odd, Space, Mark Stop bits: 1, 2 Ethernet: 2 x 10/100BaseTX RJ45, one IP with Ethernet cascade, Auto MDI/MDI-X Ethernet isolation: 1.5 kV magnetic isolation Protocols: Modbus TCP Client/Master, Modbus TCP Server/Slave, Modbus RTU/ASCII Master, Modbus RTU/ASCII Slave Max. TCP client connections: 32 Max. TCP server connections: 32 Input voltage: 12 to 48 VDC Power connector: 7-pin terminal block Relay output: 1, resistive load 1 A at 30 VDC Housing: plastic Protection rating: IP30 Mounting: DIN-rail mountable Operating temperature: standard models 0 to 60 degrees Celsius; wide-temperature models -40 to 75 degrees Celsius Storage temperature: -40 to 85 degrees Celsius Relative humidity: 5 to 95 percent non-condensing Product status: NRND legacy industrial gateway, maintenance spare for existing Moxa Modbus networks

Principle

MOXA MGate MB3270 operates as a protocol translator between Ethernet and serial Modbus networks. When a Modbus TCP master sends a request over Ethernet, the gateway converts the TCP frame into a Modbus RTU or ASCII serial frame and forwards it through the selected serial port to the connected slave device. The slave responds over the serial line, and the gateway translates the response back to Modbus TCP for delivery to the Ethernet master. In the opposite direction, a serial Modbus master can communicate with Ethernet-based slave devices through the gateway. The internal routing table maps slave IDs, IP addresses and TCP ports so that requests reach the correct device, while the traffic monitoring function records and displays Modbus activity for diagnosis. Priority control reserves immediate response for designated urgent commands. Redundant DC power inputs and the relay output support alarm reporting and continuity in industrial control cabinets.

Applications

MOXA MGate MB3270 is used to connect legacy RS-232, RS-422 and RS-485 serial instruments, PLCs, drives, meters and valves to Ethernet-based SCADA, HMI and control systems. It fits packaging machines, production lines, gantry and conveying systems, water and wastewater plants, power and utilities, sugar mill and pulp mill automation, mining equipment, ports and material handling, as well as chemical and process automation retrofit projects. In existing installations originally equipped with the MB3270, the unit serves as a direct drop-in replacement spare, compatible with the original serial wiring, Ethernet cabling and SCADA Modbus configuration.