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In the rapidly evolving world of industrial automation and power distribution, reliable communication is critical. For decades, the IEC 60870-5 standards have been the backbone of reliable data transmission in SCADA (Supervisory Control and Data Acquisition) systems.
If you are working with power grids, substations, or renewable energy management, you have likely encountered two acronyms: IEC 101 and IEC 104. But what exactly are they, and how do they differ? More importantly, how can you deploy them easily?
1. What are IEC 101 and IEC 104?
Both protocols belong to the IEC 60870-5 standard series, designed specifically for telecontrol—the monitoring and controlling of geographically widespread processes.
l IEC 60870-5-101 (IEC 101)
Think of IEC 101 as the classic foundation. It defines the communication profile for transmitting basic telecontrol messages between a central station and an outstation (Remote Terminal Unit, RTU).
The Medium: It operates primarily over serial interfaces such as RS-232 and RS-485.
The Vibe: Low bandwidth, long-distance, highly robust for direct point-to-point connections.
l IEC 60870-5-104 (IEC 104)
IEC 104 is the modern evolution. It takes the application data from IEC 101 and wraps it for transport over standard networks.
The Medium: It operates over Ethernet networks using the TCP/IP suite.
The Vibe: High-speed, network-capable, ideal for connecting devices over LAN, WAN, or the Internet.
2. How Do They Work?
While they share the same goal, their internal structures reflect their transport mediums.
2.1. The IEC 101 Structure
IEC 101 uses a simplified three-layer model (Physical, Link, Application) based on the EPA (Enhanced Performance Architecture).
l Physical Layer: Defines the hardware (e.g., V.24/V.28).
l Link Layer: Ensures data integrity using FT1.2 frame formats.
l Application Layer: Contains the ASDU (Application Service Data Unit), which holds the actual data (e.g., "Switch Closed," "Voltage = 220V").
2.2. The IEC 104 Structure
IEC 104 encapsulates the IEC 101 data into TCP/IP packets.
l Transport Interface: Instead of the classic Link Layer, IEC 104 uses the APCI (Application Protocol Control Information).
l Mechanism: It establishes a TCP connection (typically on port 2404) and relies on standard TCPmechanisms for packet loss recovery and ordering, making it incredibly reliable over complex networks.
2.3. Key Takeaway
IEC 104 is essentially IEC 101 adjusted for the modern Internet age.
Compare | IEC 60870-5-101 | IEC 60870-5-104 |
Transmission medium | Serial (RS-232/485) | Ethernet (TCP/IP) |
Communication mode | Point-to-point / Polling | Multi-point concurrency, networking |
Data rate | Low（≤19.2kbps） | High（>10Mbps） |
Security mechanisms | Simple verification | Reliable TCP transmission, compatible with SSL/VPN |
Topology mode | Single master, multiple slaves | Multiple master and multiple slave, cross network |
Configuration complexity | Simple | High (requires network configuration) |
Compatibility | High compatibility with older equipment | Seamless integration with SCADA systems. |
3. What Can These Protocols Do?
These protocols are the language of the power grid. They allow Master stations (Control Centers) to talk to Slave stations (RTUs/PLCs) to perform three critical tasks:
l Telemetering (Monitoring): Reading analog values like voltage, current, frequency, and temperature in real-time.
l Telesignaling (Status): Reporting the status of equipment, such as whether a circuit breaker is "Open" or "Closed," or if an alarm has been triggered.
l Telecontrol (Command): Sending direct commands from the center to the field to open a valve, trip a breaker, or reset a relay.
Without these protocols, Smart Grids would simply be “Grids” blind and uncontrollable.
4. WLINK Routers Now Support IEC 101 & 104
WLINK is proud to announce that its Industrial Routers now fully support both IEC 101 and IEC 104 protocols.
Why does this matter to you?
l Seamless Conversion: You can now connect legacy IEC 101 serial devices directly to WLINK router, which can convert and transmit that data via IEC 104 over 4G/5G networks to your SCADA center.
l Cost Efficiency: No need to buy expensive, standalone protocol gateways. The WLINK router handles both connectivity and protocol translation.
l Rugged Reliability: WLINK routers are built for the harsh environments where IEC 101/104 are used—substations, solar farms, and remote utility sites.
l Typical Scenario.
Imagine a remote substation with an older RTU that only speaks IEC 101 (serial). By connecting it to a WLINK router, the serial data is read, encapsulated, and transmitted to the control center over an LTE cellular network using IEC 104 (TCP/IP).
The transition to Smart Grids requires hardware that is as versatile as the communication standards it supports. With native support for IEC 101 and 104, WLINK routers are ready to be the cornerstone of your Industrial IoT projects.
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