The Design Of The Low Power Wireless Remote Control System Of The Welding Machine

In civil engineering, industrial manufacturing fields, welding source is widely used for welding of steel structure or alloy material etc. Along with the development of technology, the requirements for the more advanced welding source are increasing, thus the gas and pulse welding source appeared, and the adjustable welding parameters are also increasing. Because of some distance between the welding workplace and welding source, a remote controller is needed to adjust the parameters of the welding source conveniently, although the welding source has the panel to adjust these parameters. So a wireless remote control system has been designed based on the low energy Bluetooth technology, which makes the welding parameters check and adjust more convenient.Firstly, the link layer protocol based on the wireless transceiver nRF24L01 and application layer protocol for the wireless remote control system is designed based on the low energy Bluetooth protocol in this paper. In order to ensure the reliability and validity of the communication between the wireless remote controller and the welding source, the short frame technology, cyclic redundancy check(CRC), automatic request retransmission (ARQ) and overtime retransmission mechanism is used in the communication protocol. Secondly, according to the function requirement, the overall planning and design have been done for the hardware and software of the remote control system. An independent Bluetooth module is added in the display panel's serial port of the welding source to avoid modifying the welding power to a great extent due to introduction of the remote control system. Bluetooth module is transparent for welding source, so the application software of the welding source can be used only a little modification needed. The remote controller just increased keys and LCD on the Bluetooth module, and the appearance and the menu of the remote controller has been designed.Thirdly, there are many layers in the software hierarchy of the remote control system. The application software in the upper layer of the software hierarchy realized the basic structure and operation of the menu, and displays the state information of the welding source. The communication software in the middle layer realized application layer protocol. Application layer protocol is a group of unified command function called by application software, these command function is a result of the abstraction and classification of the remote control system's functions. The application command function is implemented by a group of general functions, which send and receive the data. Send function takes packets from application layer into sending buffer, and the receive function takes data from receiving buffer for the application layer. These two buffers are the serial port's sending and receiving buffers in welding source, and are the shared sending and receiving buffers between the application layer and the link layer in remote controller. The link layer communication software in the lower layer sends data in the sending buffer to the air at the appropriate time, and receives data from the air interface and takes it into receiving buffer. The main functions of the link layer communication software are creating connection, monitoring connection, and sending or receiving data for the upper application software, they all together realized the remote control system's communication function.Finally, considering the remote control is used batteries to power, so the power consumption must be toke into consideration. The low power consumption MCU, communication module and LCD module are chose. In these devices, the LCD backlight consumes more power, so the electronic switch has been inserted into the power and the LCD backlight, the power supply of the LCD backlight will be cut off if no buttons be pushed in a period of time. Also considering the system's anti-interference ability, the wiring is special considered in the design of PCB board with copper pour. The software, especially the communication software, monitors the link connection with the timer, once the connection loss, new connection will be established as soon as possible, thus enhanced the system applicability.