The Design And Implementation Of The Ship Data Acquisition Module Based On CAN Bus

The shipbuilding industry is a modern comprehensive industry which provides technical equipments for water transportation,ocean development and national defense construction.To build China into a maritime power,it is the key to improve the level of ship antomation technology.The ship monitoring and alarm system as an important part of ship automation,which is able to monitor the running status of the master and auxiliary equipment and be sound and light alarm,ensures safety of the ship and stable running and reminds of the people in the ship.The design and implementation of the ship data acquisition module is just the part of the ship engine room monitoring alarm system which based on fully distributed.It is on the low-leve and the most critical part.Ship engine room data acquisition module is the field intelligent device with the functions of data acquisition,data processing,operation control and data output and so on.In this paper,based on microcontroller STM32F107VC the digital input,digital output,RTD signal input and thermocouple signal input modules are designed and implemented with dual redundant CAN bus.The CANopen protocol on the application layer is as the communication protocol of CAN bus,and follow the framework for maritime electronics.CANopen protocol defines the ship data transmission in detail,and is widely used in ship automation area.According to the overall design scheme,each ship data acquisition module is designed and implemented.STM32F107VC is chosen as main controller and TJA1050 is chosen as CAN transceiver of the module.The module uses ADUM1201 to perform photoelectric isolation between them to realize anti-jamming ability.Firstly,the digital input module,digital output module,RTD signal input module and thermocouple signal input module are designed within Altium Designer environment.The digital input acquisition realizes the collection and output of sixteen channels digital signals.The digital output module realizes the function of eight channels relays' normally open and normally closed.RTD signal input module with integrated RTD digital converter MAX31865 and thermocouple signal input module with K-thermocouple data converter MAX6675 both convert analog signals to digital signals,and transmit them to the main controller by SPI serial bus,then realize the functions of data processing and o transmission.Secondly,the software is programmed by C language within Keil uVision4 software development environment,realized the functions of each module's data acquisition and data communication.The upper application CANopen protocol based on CAN bus is as the communication protocol of the system,including object dictionary,heartbeat packets,SDO,PDO and redundancy PDO transmission,active bus switch follow the frameword for maritime electronics.Finally,through the whole network testing each data acquisition module's function,acquisition precision and redundant CAN bus communication performance have reached the standard for ship device detection.