In the field of modern industrial automation, there is an increasing demand for flexible, compact, and powerful I/O systems. Faced with diversified fieldbus protocols, complex sensor/actuator interfaces and harsh environmental conditions, a platform that can provide a unified and modular solution is crucial. This article aims to explore in depth a highly modular automated terminal system - the Inline product series. This system provides an ideal technical foundation for building distributed control systems due to its tool free installation, automatic electrical connections, support for multiple voltage regions, and extensive fieldbus compatibility. This article will provide a detailed analysis of its core architecture, electrical principles, safety mechanisms, and key engineering application points based on its system manual.
System Overview and Core Design Philosophy
The Inline automation terminal series is an open, flexible, and highly modular I/O system. It is not a simple product collection, but a uniformly designed platform that allows users to combine various functional terminals like building blocks according to specific application needs, thereby constructing a compact and efficient station structure.
1. Modularization and toolless installation
One of the most prominent features of this system is the convenience of physical installation. All terminals and modules can be directly connected to standard 35mm DIN rails without the need for any installation tools. When adjacent terminals are sequentially plugged in, their electrical connections (including data communication and power supply) will be automatically established. This "plug and play" mechanical design greatly simplifies system assembly and post maintenance, and the replacement of a single terminal does not affect the wiring of the entire site.
2. Unified product series architecture
The Inline product series mainly consists of the following parts:
Bus coupler: The "brain" of a site, responsible for connecting the local bus to higher-level fieldbus networks (such as PROFINET, EtherNet/IP, INTERBUS, etc.). It manages the data exchange of all I/O terminals within the station.
I/O Terminals: The "hands and feet" of the system, used to connect actual sensors and actuators. This includes rich functions such as digital input/output, analog input/output, temperature measurement, position detection, serial communication, etc.
Power&Segment Terminals: The "heart" of the system, responsible for providing and distributing power to different circuits within the station. They are key to achieving electrical isolation and creating independent power supply areas.
Function Terminals: including programmable controllers (Inline controllers), safety modules, intrinsically safe terminals for explosion-proof areas, etc., expand the system's capabilities in control and safety.
Voltage Region and Product Classification
In order to safely handle various signals from low voltage signals to driver level power supplies, Inline terminals are divided into different product groups based on their applicable voltage ranges and functions, and are clearly identified through color coding to prevent incorrect connections.
1. SELV area (24V DC)
This is the most common voltage region in I/O systems, used to connect standard sensors, actuators, and logic circuits.
Low level signal terminal: The casing is green, and the connector is green or black. Used for digital/analog signal processing.
Security terminal: The shell is yellow and is used to construct a safety circuit that complies with EN ISO 13849-1 standard.
DALI terminal: The casing is gray and is used to connect to DALI lighting control systems.
2. Low voltage area (120V/230V AC)
This area is used for direct control of AC loads, such as contactors, valves, etc.
The terminal and connector are both equipped with gray shells and white lightning markings.
There is a dangerous contact voltage when operating such terminals, and safety regulations must be strictly followed. Plugging and unplugging operations are only allowed in a power-off state, and the system must be connected to a grounded AC power grid.
3. Power level terminal (400V AC)
This area is used for direct control and protection of three-phase standard motors. These terminals use specialized power enclosures and are not powered by internal potential jumpers. Instead, they are connected to the 400V main power supply through independent power connectors and bridges.

Electrical Architecture: Potential and Data Routing
The core advantage of the Inline system lies in its internal potential and data jumper system. When the terminals are correctly installed, these jumpers will automatically establish connections between adjacent terminals, forming an internal power and data bus, greatly reducing the number of external jumper wires.
1. Internal potential jumper
Multiple parallel potential jumpers are defined within the system, which run vertically through all terminals and provide power to different circuits