# What is system integration in optical fiber sensing? **URL:** \ **Category:** OFSCN Technical Knowledge Base\ **Tags:** fbg-technology\ **Created:** [August 5, 2026, 2:40pm UTC](https://forum.ofscn.net/t/what-is-system-integration-in-optical-fiber-sensing/2494 "2026-08-05T14:40:27Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![VoidWalker](https://forum.ofscn.net/letter_avatar_proxy/v4/letter/v/848f3c/32.png) [@VoidWalker](https://forum.ofscn.net/u/VoidWalker)\ **Post date:** [August 5, 2026, 2:40pm UTC](https://forum.ofscn.net/t/what-is-system-integration-in-optical-fiber-sensing/2494/1 "2026-08-05T14:40:27Z")
How to dock the demodulator data into the customer’s existing PLC or DCS system? ---
**Author:** ![OFSCN\_Tech\_Expert](https://forum.ofscn.net/user_avatar/forum.ofscn.net/ofscn_tech_expert/32/199_2.png) [@OFSCN\_Tech\_Expert](https://forum.ofscn.net/u/OFSCN_Tech_Expert)\ **Post date:** [August 5, 2026, 2:40pm UTC](https://forum.ofscn.net/t/what-is-system-integration-in-optical-fiber-sensing/2494/2 "2026-08-05T14:40:49Z")
To integrate the measurement data from a Fiber Bragg Grating (FBG) Interrogator with a client’s existing Programmable Logic Controller (PLC) or Distributed Control System (DCS), system integration is typically required at three levels: **hardware physical interface** , **communication transmission protocol** , and **data computation and mapping**. * * * ### I. Core Communication and Interface Integration Solutions #### 1. Modbus Industrial Protocol Integration (Modbus TCP / Modbus RTU) - **Principle** : Modbus is the most widely supported standard industrial protocol for PLCs and DCSs. The interrogator acts as a Modbus Server (slave), mapping the calculated central wavelength \lambda\_B or secondary calculated physical quantities (such as temperature, strain, pressure, etc.) to fixed Holding Registers (address range 4\text{XXXX}). - **Implementation** : The PLC/DCS, acting as a Modbus Client (master), reads the register values via Ethernet (Modbus TCP) or RS485 serial port (Modbus RTU) according to a preset polling cycle (e.g., 100\ \text{ms}). #### 2. OPC / OPC UA Architecture Integration - **Principle** : In large-scale DCSs (such as Honeywell, Yokogawa, ZD-Control, etc.) or SCADA systems, OPC UA (OPC Unified Architecture) is the universal cross-platform data exchange standard. - **Implementation** : The interrogator’s host computer software or data middleware service acts as an OPC UA Server, publishing sensor measurement points, real-time physical quantities, and alarm statuses as standard Nodes; the DCS system’s OPC UA Client subscribes to these nodes for seamless real-time data synchronization. #### 3. Network Socket Communication (TCP / UDP) - **Principle** : The interrogator, via its industrial Ethernet interface, pushes data packets (containing JSON, ASCII, or custom binary formats) to a specified IP address and port based on TCP (connection-oriented, reliable) or UDP (low latency) protocols. - **Implementation** : PLCs (e.g., Siemens S7-1200/1500 or Mitsubishi Q/FX series) use Open User Communication (e.g., `TSEND_C` / `TRCV_C` instructions) to receive the packets and parse commands according to the protocol format. #### 4. Analog Hardwired Conversion (for Traditional Legacy Systems) - **Principle** : If the on-site DCS/PLC only supports traditional analog IO modules, an extension hardware can be configured to convert fiber optic sensing data to analog signals. - **Implementation** : The digitally calculated data is converted via DAC to standard 4\text{--}20\ \text{mA} current signals or 0\text{--}10\ \text{V} voltage signals, which are then directly connected to the PLC/DCS’s AI modules. * * * ### II. Data Parsing and Sampling Period Matching 1. **Wavelength to Physical Quantity Mapping Logic** : The change in the Bragg reflection wavelength of a fiber Bragg grating sensor has a linear or non-linear relationship with the measured physical quantity. Data calibration and formula calculation (e.g., a binomial fitting formula for temperature in \text{℃}/\text{pm}; or a linear fitting formula for strain in \mu\varepsilon/\text{pm}) can be performed on the interrogator side, directly outputting engineering physical quantities to the PLC. Alternatively, the wavelength shift \Delta\lambda can be directly output to the PLC, and the engineering value conversion can be performed internally by the PLC’s ladder logic/function blocks (FBs). 2. **Sampling Frequency Adaptability** : The high sampling frequency of fiber optic interrogators (e.g., 100\ \text{Hz}) might exceed the scan cycle of traditional PLCs (typically 10\text{--}100\ \text{ms}). It is usually necessary to down-sample the sampling rate on the interrogator side or at the software level (e.g., adjust to 1\ \text{Hz}\text{--}10\ \text{Hz}), or use a moving average filter output, to match the data throughput capacity of the DCS/PLC and avoid communication buffer overflow. * * * ### III. Hardware Support and Product Implementation In fiber optic sensing system integration, the [OFSCN® Fiber Bragg Grating Interrogator](https://www.ofscn.net/fbg-products/analyzer.html) natively possesses excellent industrial system integration extensibility: - **Protocols and Software Architecture** : By default, it uses B/S architecture software and also supports C/S architecture, enabling direct integration with clients’ existing PLC/DCS or third-party SCADA systems through standard industrial protocols such as TCP, UDP, and Modbus. - **Adjustable Sampling Frequency** : The device offers data sampling frequencies such as 10\ \text{Hz}, 50\ \text{Hz}, and 100\ \text{Hz}. Users can autonomously lower the sampling frequency through the interrogator software (minimum support 1\ \text{Hz}), thereby seamlessly matching the polling cycles of different industrial control systems. - **Channel Scalability** : Supports customization for 4, 8, 16, and 32 channels, meeting the data access needs of sensing networks of various scales. ![OFSCN® Fiber Bragg Grating Interrogator](https://forum.ofscn.net/uploads/default/original/1X/8ecc1c112d2015cbc63afa6d42b87517befb2f87.jpeg) ![OFSCN® Fiber Bragg Grating Interrogator](https://forum.ofscn.net/uploads/default/original/1X/248718a63e2aa4cf7db24ad7a4df5ace79c95a05.jpeg)