Moxa MGate 5109 Modbus to DNP3 Gateway

Linking Modbus devices and DNP3 SCADA in utilities

The Moxa MGate 5109 is a one-port gateway for Modbus RTU/ASCII/TCP and DNP3 serial, TCP and UDP. Moxa positions it for power, oil and gas, and water and wastewater, where DNP3 masters and outstations are common. In transparent mode it joins Modbus TCP to Modbus RTU/ASCII, or DNP3 TCP/UDP to DNP3 serial networks. In agent mode it exchanges data between Modbus and DNP3 networks or concentrates many Modbus slaves or DNP3 outstations into one connection. It supports DNP3 master and outstation (Level 2), DNP3 time synchronisation, and a master database of up to 26,600 points. A web wizard and a protocol traffic monitor make commissioning easier.

Technical specifications

Ordering codes

The package contains an RJ45-to-DB9 console cable, a DIN-rail kit, a quick installation guide and a warranty card.

Key features of the MGate 5109

• Protocol conversion between Modbus RTU/ASCII/TCP and DNP3 serial/TCP/UDP in one compact DIN-rail unit.
• Transparent mode for Modbus-to-Modbus or DNP3-to-DNP3 media conversion, and agent mode for true Modbus-to-DNP3 data mapping.
• DNP3 master and outstation roles, so the gateway can poll field devices or present data to an upstream SCADA master.
• Dual redundant 12–48 VDC power inputs and a relay output for alarm signalling to the control system.
• Security functions including HTTPS with TLS 1.3, SSH and SNMPv3 for remote management over utility networks.
• Two Ethernet ports for cascading, reducing the number of switch ports needed in a small panel.

Transparent mode or agent mode?

In agent mode the gateway keeps an internal database: it polls one side and serves the data to the other, so response times on the SCADA side do not depend on the speed of the serial network.

Applications in Oman and the GCC

Electricity distribution companies, water and wastewater operators and oil and gas producers in Oman and the Gulf commonly run DNP3 SCADA systems that must collect data from Modbus equipment at substations, pumping stations, reservoirs and wellheads. The MGate 5109 sits in the RTU or telemetry panel and connects energy meters, flow computers, VFDs and small PLCs to the DNP3 master. Many of these sites are unmanned and exposed to high temperatures. The standard model is rated 0 to 60 °C; for outdoor kiosks without air conditioning, the wide-temperature MGate 5109-T rated −40 to 75 °C is the safer choice. The listed ATEX, Class I Division 2 and IECEx approvals are relevant to installations in classified areas of oil and gas facilities, subject to the installation conditions in the certificates.

Commissioning and maintenance tips

• Prepare a point list mapping each Modbus register to a DNP3 object, index and class before configuring the gateway.
• Match baud rate, parity and stop bits exactly to the serial devices, and terminate the RS-485 bus at both ends.
• Use the traffic monitor during start-up to confirm polling and responses.
• Save a configuration backup to the microSD card and to the engineering file after every change.
• Change default passwords and disable unused services before connecting the unit to a SCADA network.

What to include in your RFQ

State the model (MGate 5109 or MGate 5109-T), quantity, required hazardous-area approvals, the protocols on each side and the number of devices and points, so the suitability of the gateway can be confirmed before order.

Where it fits and what to confirm

Typical uses are remote terminal units, substations and pump stations where a DNP3 master must read Modbus meters, or where a Modbus SCADA must read DNP3 outstations. Auto Detection of serial DNP3 outstations acquires objects automatically when the unit is the DNP3 master. Before ordering, confirm the DNP3 level and objects your master requires, the point counts per outstation, and whether DNP3 time synchronisation is needed. For IEC 60870-5-101/104 networks, see the MGate 5114. Seven Star LLC, an independent supplier in Muscat, quotes the exact model and temperature range. The datasheet (version 1.6) is attached, and related products are in Industrial Communications. The gateway keeps firmware logs of connection and Modbus maintenance events that can be read through the web console, and the Protocol Traffic Monitor captures Modbus and DNP3 frames to expose wrong slave IDs, register addresses or command settings during installation. HTTPS and SSH protect remote maintenance. A microSD card stores configuration backups and event logs so a replacement unit can be configured quickly. Environmental tests listed include shock (IEC 60068-2-27), vibration (IEC 60068-2-6 and -64) and free fall (IEC 60068-2-32), and the EMI class is FCC Part 15B Class B. DNP3 master mode supports up to 26,600 points, with 256 binary points and 64 analog points per outstation in the internal database. The two Ethernet ports allow daisy-chaining of neighbouring devices without an additional switch.