Abstract: Elevators are an indispensable means of transportation in modern high-rise buildings, and most elevators currently use PLC control. This paper proposes a design method for an elevator control system based on Lonworks fieldbus technology. The paper first introduces an overview of Lonworks fieldbus technology, and then focuses on the hardware composition of the elevator control system: the elevator control system consists of four parts, namely, the elevator control hardware model, the control module, the LonBuilder development platform, and the local monitoring machine. A program is also developed to schedule elevator operation. Experimental tests have achieved the expected results. Keywords: Lonworks technology; elevator control model; control system 1 Overview of LonWorks Fieldbus Lonworks technology is a fieldbus technology launched by Echelon Corporation in the early 1990s. It provides a highly open local operating network, with significant features including powerful neural network chips, system interoperability, and the LonTalk communication protocol. The Lonworks network system consists of intelligent nodes, each of which can have various forms of I/O functions, and nodes can communicate with each other through different transmission media. Lonworks technology includes a complete set of methods for the design, development, installation, and debugging of the monitoring network. Dedicated hardware devices and software programs are required. The main components include: Neuron Chip: The Neuron Chip is the core hardware of Lonworks technology, containing three 8-bit pipelined CPUs. Six layers of the seven-layer communication protocol are embedded in on-chip memory; only the seventh layer requires user programming. The maximum clock frequency is 10MHz. It features two 16-bit timers/counters, a 48-bit encoded internal identifier (Neuron ID), and a service pin for remote identification and diagnostics. LonTalk Communication Protocol: LonTalk is the standard communication protocol for Lonworks technology, supporting various transmission media such as twisted pair, power line, fiber optic, and infrared. Each medium has a dedicated transceiver as the interface between the intelligent node and the communication medium. Routers are used to connect different channels. The LonTalk protocol supports Neuron C language programming, enabling communication between nodes through network variables. Development Tools: Lonworks offers two development tools: LonBuilder and NodeBuilder. Both consist of both hardware and software components. LonBuilder is a system-level development tool that provides a PC-based development environment that supports simulation of single or multiple nodes. Its hardware includes a PC adapter card, LonBuilder processor board, Neuron C emulator, LonBuilder single-board computer, router, transceiver debug board, etc. The LonBuilder application programming software provides all the tools needed to edit, compile, debug, and test Neuron C software, including a Neuron C compiler and Neuron C debugger. It also includes network management tools and a startup workkit. NodeBuilder, on the other hand, is a device-level development tool used to program and debug single nodes. Its hardware includes a PCNSS card, LTM-10 LonTalk protocol node, Motorola Gizmo3, and SMX-compatible transceivers. The software programming language is also Neuron C. 2. Hardware Composition of the Elevator Control System The elevator control system consists of four parts: the elevator control hardware model, the control module, the LonBuilder development platform, and the local monitoring unit. Figure 1 below shows the composition of the elevator control system. [align=center] Figure 1 Composition of the elevator control system[/align] 2.1 Elevator Group Control Hardware Model The elevator model of the elevator control system includes one elevator with a total of 7 floors. It consists of an elevator car, a car control motor, and limit switches for each floor. In addition, the model also includes a set of external call buttons and corresponding indicator lights, internal call buttons and corresponding indicator lights, floor display, passenger display, up and down indicator lights, door open/close buttons and control motors, and passenger increase/decrease buttons, etc. 2.2 Control Module The control module uses Lonworks intelligent control modules produced by Beijing Xinhua Yizhong Technology Co., Ltd. Each module consists of 8 digital inputs, 8 digital outputs, a Lon network port, a power input port, ground, a Service key, and a reset key. This elevator control system model consists of 5 such control modules. The specific connection of the 5 control modules is as follows: Module 1 connects to 1 elevator motor, 7 floor limit switches, 1 floor display, and up and down indicator lights. (7 In, 7 Out) Module #2 connects to 8 external call buttons (1, 2 Down, 2 Up, 3 Down, 3 Up, 4 Down, 4 Up, 5 Down) and 8 corresponding indicator lights. (8 In, 8 Out) Module #3 connects to 4 external call buttons (5 Up, 6 Down, 6 Up, 7) and 4 corresponding indicator lights. (4 In, 4 Out) Module #4 connects to 7 internal call buttons (1, 2, 3, 4, 5, 6, 7) and 7 corresponding indicator lights. (7 In, 7 Out) Module #5 connects to 1 car motor, 2 car switches, 2 car limit switches, 1 passenger display for both passengers entering and leaving the elevator, and 2 simulated passenger entry and exit buttons. (6 In, 6 Out) These five modules constitute the control module for controlling the elevator's operation. The written program is downloaded to these five modules, and the elevator model will then operate according to the programmed algorithm. The written program is downloaded via the Lon port. 2.3 Lonbuilder Development Platform and External Connections The Lonbuilder development platform integrates three tools—a multi-node development system, a network manager, and a protocol analyzer—forming a simple and easy-to-use development environment. It primarily provides tools for building application software and testing node development network hardware. Free Topology Transceiver FTT-10. The FTT-10 transceiver provides a fast twisted-pair transceiver for integrating external nodes with nodes on the Lonbuilder development platform to create simulated networks. DDE Server. The DDE server supports any Windows application software with dynamic data exchange capabilities and provides a graphical user interface for quickly building Lonworks networks. PCNSI PC Network Service Interface and Connectivity Package. PCNSI provides a high-performance network interface for using the DDE server, the Windows LNS development kit, and user-defined applications. Development Station Hardware. The development station hardware includes two Lonworks nodes, one for network management and one for protocol analysis. Currently, we are using the Lonbuilder experimental platform, which can accommodate up to five emulators; we currently have two emulators installed. These Lonworks nodes run and debug Neuron C programs via the debugger, and can test I/O testbeds and transceiver hardware. Two emulators can communicate with each other, allowing for synchronous debugging of applications between two interacting Lonworks nodes. The LonBuilder interface adapter and interface cable are 8-bit ISA-compatible cards that plug into the ISA slot on our experimental system platform, providing high-speed connectivity between local monitoring and development stations. The Lonworks transceiver kit includes one LonBuilder SMX adapter and four FTT-10 free-topology transceivers. The PCNSI PC interface card provides a high-performance interface between the ISA bus PC and the Lonworks network. The Lonbuilder router supports network development using various communication channels and media, facilitating connections between development stations and various types of external networks. The structural composition of the Lonbuilder development platform is shown in Figure 2. [align=center]Figure 2. Composition Structure Diagram of Lonbuilder Development Platform[/align] The external connection of the Lonbuilder development platform is as follows: The back of the development platform is connected to the parallel port of the host PC via a parallel port. The front of the development platform is connected to the LonBuilder control processor, Neuron emulator, and LonBuilder router via twisted-pair cables. These twisted-pair cables are then connected to the Lon port of the control module. This allows the Neuron C program written on the PC to be downloaded to the control module, enabling the module to operate independently of the development platform and control the elevator model's program. 2.4 Local Monitoring Unit The local monitoring unit is a PC. The PC is connected to the control module and elevator model via the Lonbuilder development platform. Visual Basic can be used as the programming language on the PC. The program is mainly used to synchronously display the elevator's operating status. With further research, a remote monitoring system can be formed using a network and machines in more distant locations. 3 Software Design The developed system is programmed using Neuron C. The entire system sets 10 standard network variables. The specific functions are as follows: Nvi-Floor represents the network input for external floor calls; Nvo-Floor represents the network output for external floor calls; Nvi-inFloor represents the network input for internal floor calls; Nvo-inFloor represents the network output for internal floor calls; Nvi-Floorled represents the network input for controlling the cancellation of the external call light; Nvo-Floorled represents the network output for controlling the cancellation of the external call light; Nvi-inFloorled represents the network input for controlling the cancellation of the internal call light; Nvo-inFloorled represents the network output for controlling the cancellation of the internal call light; Nvi-Door represents the network input for controlling the door opening and closing; Nvo-Door represents the network output for controlling the door opening and closing. The basic design idea of ​​the entire program is: elevator call signals are divided into external call signals and internal call signals. External call signals are further divided into external call up signals and external call down signals. Three arrays are designed to store the three types of elevator call signals respectively. When the program resets, the elevator stops at the first floor. Whether the elevator stops is determined based on the elevator call signal. If the elevator is currently moving upwards, and the current floor equals the called floor, the elevator stops; if the called floor is greater than the current floor, the elevator continues upwards; if the called floor is less than the current floor, the elevator continues upwards if someone is present, and descends if no one is present. If the elevator is currently moving downwards, and the current floor equals the called floor, the elevator stops; if the called floor is less than the current floor, the elevator descends; if the called floor is greater than the current floor, the elevator continues downwards if someone is present, and ascends if no one is present. 4. Conclusion This paper mainly introduces the composition of an elevator control system designed based on Lonworks fieldbus technology, and describes the program designed on this hardware platform. Actual testing shows that the designed program achieves a relatively ideal scheduling effect. The feasibility of the elevator control system design is also verified. 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