Modbus to IEC 60870-5-104 Gateways

Connecting Modbus Field Devices to Power SCADA Systems Over IEC 104

IEC 60870-5-104 is the international standard for SCADA 
communication in power systems used by grid operators, 
utilities, and energy management centers worldwide to 
monitor and control substations, distribution automation 
equipment, and remote field sites over TCP/IP networks. 
Modbus RTU and TCP, by contrast, are the dominant 
protocols for field-level instruments: power meters, 
protection relays, RTUs, and energy monitoring devices 
that were designed for plant-floor communication, not 
utility-grade telemetry.

When a power SCADA or Energy Management System (EMS) 
operating on IEC 60870-5-104 needs to access data from 
Modbus field devices, a Modbus to IEC 60870-5-104 gateway 
provides the correct protocol translation. The gateway 
collects data from Modbus RTU or TCP devices and presents 
it to the IEC 104 master as a standard IEC 60870-5-104 
controlled station with full support for spontaneous 
event reporting, timestamped data, and general interrogation.

Why IEC 104 Is Fundamentally Different from Modbus

The difference between Modbus and IEC 60870-5-104 goes 
beyond protocol syntax. Modbus is a purely polling-based 
protocol the master always initiates, and slaves only 
respond when asked. IEC 60870-5-104 supports spontaneous 
event transfer, where the controlled station can report 
data changes to the control center without being polled, 
and timestamped data objects, which allow historical 
event reconstruction even after a communication outage. 
A Modbus to IEC 104 gateway must therefore do more than 
pass registers through it must map Modbus register 
values into IEC 104 data objects with correct ASDU types, 
Information Object Addresses, and Common Addresses, 
while handling event buffering and spontaneous reporting 
on behalf of the connected Modbus devices.

Industries and Applications

Modbus to IEC 60870-5-104 gateways are primarily deployed 
in power substations integrating Modbus energy meters, 
protection relays, and IEDs into IEC 104-based SCADA 
and EMS systems, in electricity distribution networks 
where Modbus RTU field devices at transformer stations 
must report to a central IEC 104 control center, in 
renewable energy installations connecting Modbus-based 
inverters, solar meters, and wind turbine controllers 
to utility-grade SCADA platforms, and in water and 
wastewater infrastructure where Modbus PLCs at remote 
pump stations must integrate with IEC 104 supervisory 
systems used by public utility operators.

Engineering Support from Archonwell

Modbus to IEC 60870-5-104 integration requires careful 
mapping of Modbus registers to IEC 104 ASDU types and 
Information Object Addresses, configuration of Common 
Address settings, and verification of spontaneous 
reporting behavior against the SCADA master. 
Archonwell's engineering team provides full application 
support for utility and infrastructure projects across 
Thailand from gateway configuration through to 
on-site commissioning and SCADA system verification.