Moxa MGate 5114 Modbus to IEC 60870-5-104 Gateway

Feeding power SCADA with IEC 60870-5-104 from Modbus and IEC 101 devices

The Moxa MGate 5114 is a one-port gateway for Modbus RTU/ASCII/TCP, IEC 60870-5-101 and IEC 60870-5-104. It lets power utilities and industrial plants connect field devices that speak different protocols to a power SCADA system. The unit can collect data as a Modbus master or client or as an IEC 101 master and present it as an IEC 104 server, and it can also run as IEC 101 slave (balanced or unbalanced) or IEC 104 client. A web wizard guides setup, a protocol traffic monitor writes logs that can be opened in Wireshark, and status monitoring tells the power SCADA when an end device disconnects or stops responding.

Technical specifications

Ordering codes

Key features of the MGate 5114

• Protocol conversion in both directions: Modbus RTU/ASCII/TCP and IEC 60870-5-101 devices can be presented to an IEC 104 SCADA, or IEC 104 data can be passed down to IEC 101 or Modbus equipment.
• Two Ethernet ports for cascading: several gateways can be daisy-chained, reducing switch ports in a small substation panel.
• Isolated serial port: 2 kV isolation on the RS-232/422/485 port helps in electrically harsh switchgear rooms.
• Troubleshooting tools: the protocol traffic monitor and Wireshark-compatible logs shorten commissioning and fault finding.
• microSD storage: configuration backup and event logs on a card make unit replacement fast.
• Security functions: HTTPS, SSH, SNMPv3 and encryption support help meet utility cybersecurity requirements.

Typical architectures

Modbus devices to an IEC 104 control centre

The most common use is a secondary substation, solar plant or pumping station with Modbus energy meters, protection relays, inverters or PLCs. The gateway polls them as Modbus master or client and maps each register to an IEC 104 information object, which the control centre reads as if the field devices spoke IEC 104 natively.

Migrating IEC 101 serial links to IP

Where older RTUs or relays use IEC 101 over serial links, the gateway acts as IEC 101 master and republishes the data over IEC 104, allowing a utility to move from serial radio or leased lines to an IP network without replacing the field equipment.

Engineering the data mapping

Plan the point list before configuration: for each signal, record the source device address, register or object address, data type, scaling, and the target IEC 104 type identification and information object address. Agree with the SCADA team whether measurements are sent as normalised, scaled or short floating point values, and whether spontaneous transmission with deadbands or cyclic transmission is expected. Clear agreement on the point list avoids most commissioning delays.

Keep the polling load within what the serial devices can handle: many slow Modbus RTU devices on one RS-485 line will increase update times. The status monitoring function should be mapped to SCADA so that a failed field device is reported as invalid rather than as frozen data.

Installation in Oman and GCC substations

Package substations, ring main unit kiosks and solar inverter stations in the region are often unconditioned and dusty. Check the operating temperature range of the selected model (standard or wide-temperature) against the expected cabinet temperature, provide sunshades or ventilation where needed, and use shielded serial cable with proper earthing. The gateway is also used by water utilities and oil and gas operators connecting field telemetry to IEC 104 systems.

What to include in an RFQ

State the model (MGate 5114 or the wide-temperature variant from the ordering codes above), quantity, the protocols on each side, the approximate number of devices and points, and whether DIN-rail power supplies or serial cables are needed.

Engineering notes

Before ordering, list the information objects (type IDs, common addresses, object addresses) your control centre expects and check them against the 2000-point limit of each IEC mode. IEC 101 balanced links allow one slave connection; unbalanced links allow up to 31. The gateway does not translate beyond what is mapped, so plan the data mapping with the SCADA vendor. For DNP3 networks rather than IEC 104, compare the MGate 5109, and for EtherNet/IP see the MGate 5105-MB-EIP. Seven Star LLC, an independent supplier in Muscat, quotes the exact code you need and the temperature range. The datasheet (version 1.5) is attached, and related products are in Industrial Communications. The system log records events inside the gateway and can be reviewed remotely through the web console. Status monitoring and fault protection let the gateway report a disconnected or silent end device to the power SCADA, which then raises alarms for operators. The microSD card stores configuration backups and event logs, and the two Ethernet ports allow daisy-chaining to the next device without an extra switch port. 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. Remote access is secured with HTTPS (TLS 1.3), SSH and SNMPv3. The IEC 104 side supports 32 client and 32 server connections, so several control centres can poll the same gateway.