Complete Guide to Inline Automation Terminal System

Inline Automation Terminal System: Architecture, Principles, and Engineering Practice of Modular I/O Platform

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

UL (7.5V DC): Communication power supply, providing power to the microcontroller and bus interface inside the terminal. Converted from 24V input by a bus coupler or specific power terminal.

UANA (24V DC): Analog voltage, supplying power to analog input/output terminals.

UM (24V DC): The main circuit power supply provides the main power for digital I/O, usually from an external power source.

US (24V DC): Segmented circuit power supply, which can be disconnected from UM through jumpers or fuses, used to create multiple load segments that can be independently protected or turned off.

GND: The common reference ground for the main circuit and segmented circuit.

FE: Functional grounding, used to improve the system's anti-interference ability.

2. Circuit segmentation and electrical isolation

By using different types of power terminals and segmented terminals, multiple electrically isolated areas can be created within a physical station. For example:

A power terminal can interrupt all incoming potential jumpers and inject new power. This allows the creation of areas with different voltages such as 24V DC and 230V AC on the same DIN rail, and achieves electrical isolation between them.

A segmented terminal only interrupts the US (segmented circuit) jumper. This allows engineers to set fuses or switches for multiple load groups under a main circuit, achieving refined power management. For example, a short circuit fault in an output module will only cause the fuse of the segment circuit it is in to actuate, without affecting other I/O modules and bus communication within the same station.

Hardware Structure and Connection Technology

1. Basic structure of terminal

Each Inline terminal is mainly composed of two parts: an electronic module base and a pluggable connector.

Electronic module base: includes all electronic components of the terminal and lateral blade contacts for potential and data routing. On the left side of the base, there is a "raised" pin arrangement, and on the right side, there is a corresponding "groove". When the terminals are installed side by side, the left pin will be precisely inserted into the groove of the adjacent terminal on the right, thereby establishing mechanical and electrical connections.

Pluggable connector: used to connect field devices (sensors/actuators) and power supply. This separated design allows for quick replacement of faulty electronic modules without dismantling any on-site wiring, greatly reducing maintenance downtime.

2. Spring connection technology

The connectors of Inline terminals commonly use spring wiring technology. This technology has advantages such as anti vibration, reliable connection, and fast operation. When wiring, simply use a screwdriver to press open the spring, insert the stripped cable, and after pulling out the screwdriver, the spring will automatically press the wire. The cross-sectional area of the connectable wires is usually 0.08 mm ² to 1.5 mm ².

3. Shielded connection

For sensitive signals such as analog signals and encoder signals that are susceptible to interference, shielded cables must be used. The Inline system provides specialized shielded connectors (such as IB IL SCN-6 SHIELD). The connector has a shielding clamping device inside, which can firmly clamp the braided shielding layer of the cable and connect it to the functional grounding (FE) potential, effectively suppressing external electromagnetic interference.

Installation and Engineering Practice Guide

Successful system design is not only about selecting the right modules, but also about following a series of engineering best practices.

1. Installation distance and heat dissipation

To ensure long-term stable operation of the system, sufficient heat dissipation space must be ensured.

For standard I/O terminals, at least 35mm-50mm of space needs to be left above and below for heat dissipation and wiring.

For power level terminals such as motor starters, due to significant power loss, the vertical installation distance requirements are more stringent to ensure free air circulation and prevent overheating.

2. Grounding and equipotential connection

Correct grounding is the cornerstone of system anti-interference and safe operation.

Functional Grounding (FE): All 24V DC terminals are connected to the galvanized DIN rail via a metal spring at the bottom. For bus couplers and power terminals, it is strongly recommended to use an additional wire to connect their FE terminals to the central grounding busbar to ensure reliable grounding even in the event of DIN rail surface oxidation or poor contact.

Protective Grounding (PE): For 120V/230V AC and 400V AC areas, their power terminals and power terminals must be reliably grounded through dedicated PE terminals. This is an important measure to ensure personal safety.

3. Terminal sorting principle

In a main circuit, the arrangement order of terminals should consider the current load and signal type.

High current priority: The digital output terminal with the highest current consumption should be placed near the power terminal. This can avoid high current flowing through the potential jumper of the entire station for a long time, thereby reducing line losses and heating.

Analog input/output terminals are sensitive to temperature changes and have low internal power consumption. They should be arranged after all high-power digital quantity terminals and located at the end of the main circuit. This can minimize the impact of temperature rise caused by high current on the accuracy of analog signals to the greatest extent possible.

Special module: Terminals with remote bus branches must be located immediately after the bus coupler or another remote bus branch terminal. The position of the safety module determines the range of subsequent safety related segmented circuits.

Diagnosis and status indication

The intuitive diagnostic function is a major highlight of the Inline system. Each terminal is equipped with LED indicator lights for quick fault location.

D LED (green): Global diagnostic indicator light. Its flashing frequency can indicate different states: constant light indicates normal data exchange; Slow flashing (0.5Hz) indicates the presence of communication power but no data exchange; Flash (4Hz) indicates poor contact or malfunction of the local bus interface between adjacent terminals, which is a key clue for troubleshooting physical connection issues.

UM/US LED (green): Indicates the presence of power supply for both the main circuit and the segmented circuit.

I/O LED (yellow): The yellow LED corresponding to each channel intuitively displays the input/output logic status of that channel.

E LED (red): Commonly seen in power terminals with fuses or I/O terminals with extended diagnostic functions. For example, on a power terminal with a fuse, if the UM LED lights up and the E LED also lights up, it clearly indicates that the fuse has blown.

Special Applications and Scalability

1. Application in explosion-proof areas (Ex i)

The Inline series provides intrinsically safe terminals (EX-IS) that allow I/O signals to be introduced into hazardous areas (Zone 1/Zone 0). Building an intrinsic safety station requires dedicated power terminals (IB IL EX-IS PWR IN-PAC) and isolation terminals (IB IL EX PWR-ISO-PAC) to ensure that energy from non intrinsic safety circuits does not enter hazardous areas. It should be noted that the effectiveness of ATEX certification is closely related to the production date of the product, and the latest compliance information must be checked during engineering design.

2. Security module

The system supports two security integration methods:

Traditional safety module (such as IB IL SAFE 2-ECO): This module is independent of the bus and directly cuts off the power supply of the subsequent segmented circuit by monitoring external safety circuits (such as emergency stop buttons) to achieve safe shutdown.

Based on security protocols such as SafetyBridge and PROFIsafe: These security modules exchange data with the security controller through a standard bus. Secure communication and standard communication are transmitted on the same cable, achieving a fully integrated security solution from the controller to the actuator.

3. Remote bus expansion and branching

Through dedicated branch terminals (such as IB IL 24 FLM-PAC), the Inline system can not only serve as a local I/O station, but also expand the connection to fieldbus modules with protection levels up to IP65/67 (such as Fieldline Modular), or achieve long-distance (cross row) hopping between stations through RS-422 protocol, greatly enhancing the flexibility of system layout.