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1. Application requirements
The system consists of a wireless ordering handheld with ZIGBEE wireless data communication function held by the waiter, or a ZIGBEE wireless ordering machine with ZIGBEE wireless data communication function installed on the dining table, and a ZIGBEE wireless data center node installed on the server side of the PC system. Using this system, waiters or customers can use the wireless ordering machine to order food, add food, and settle accounts anytime and anywhere, and transmit the data to the back-end data server in real time. On the data server side, a ZIGBEE wireless data center node is installed, which can communicate with the wireless ordering machine anytime and anywhere within the effective range, and the server is responsible for the background data maintenance and management.
The system consists of a wireless ordering handheld machine or a wireless ordering machine on the table, a wireless communication node and a PC control machine installed with a wireless ZIGBEE central node. The wireless communication node of the PC control machine is used in conjunction with the wireless ordering machine to complete the wireless data communication function of the ordering system. A ZIGBEE wireless communication center node can communicate with multiple wireless ordering machines in a polling manner. In the indoor environment, affected by factors such as the obstruction of buildings, when the communication distance of a PC-side wireless data node cannot cover the entire application site, adding multiple wireless communication routing nodes at appropriate locations can form a fairly reliable cellular network , To ensure the reliable transmission of data.
2. ZigBee-based restaurant wireless ordering system communication network
The restaurant ZigBee wireless node network constitutes a complete wireless communication network through ZigBee node equipment deployed in restaurants, bars, kitchens, checkout counters, and processing centers, realizing the automation of information processing.
A handheld ordering terminal with a built-in wireless ZIGBEE communication module. The waiter processes customer orders through the handheld ordering terminal. User orders are automatically uploaded to the kitchen and cashier through the terminal and the ZigBee network in the hall.
The ZIGBEE central node, wireless ZIGBEE router and wireless ordering terminal of the wireless communication system can form a cellular communication network, and any node can realize communication in a multi-tuning manner. Any one of the ZIGBEE routers is responsible for the connection to the central network and data relay and forwarding.
All ZIGBEE routers form a cellular mesh network, which is then connected to the ZIGBEE central node. The central node is set at the general service desk to construct a complete ZIGBEE wireless network, which is a very reliable communication network structure.
3. Introduction to Zigbee wireless technology
Zigbee is a new wireless connection technology, which mainly solves low-cost, low-power, low-complexity, low-transmission rate, and short-distance device networking applications.
The ZigBee standard is based on the 802.15.4 protocol stack and has powerful device networking capabilities. It supports three main types of self-organizing wireless networks, namely star structure, mesh structure and cluster tree. And the system node has multi-hop routing function, especially can form a cellular mesh network structure, with strong network robustness and system reliability.
Figure 1 ZIGBEE star network structure
Star network structure characteristics
Support point-to-point and point-to-multipoint communication The central node is the ZIGBEE coordinator, and the terminal node is the ZIGBEE terminal equipment. All data passes through the central node and is suitable for circularly distributed and close equipment networking.
Figure 2 ZIGBEE mesh network structure
MESH mesh network structure characteristics
The system adopts multi-hop routing communication
Large network capacity
It can span a large physical space and is suitable for structures that are far away and dispersed
The mesh network topology of the MESH network has powerful functions. All entities in the network can communicate with each other only within the communication range. If there is no direct path, they can also communicate through “multi-hop” mode; this topology It can also form a very complex network; in addition, the network also has self-organization and self-healing functions.
Fourth, the advantages of Zigbee wireless technology
Equipment power saving
The zigbee technology uses a variety of power-saving working modes, which can ensure that two AA batteries can support up to 6 months to 2 years of use;
Reliable communication
Zigbee adopts the collision avoidance mechanism of CSMA-CA, and reserves dedicated time slots for communication services that require fixed bandwidth to avoid competition and conflicts when sending data; the MAC layer adopts a fully confirmed data transmission mechanism. All data packets must wait for the receiver’s confirmation message;
Strong network self-organization and self-healing ability
Zigbee’s self-organizing function: without manual intervention, network nodes can perceive the existence of other nodes and determine
Connect relationships to form a structured network;
Zigbee self-healing function: add or delete a node, the position of the node changes, the node fails, etc.,
The network can repair itself, and adjust the network topology accordingly, without manual intervention, to ensure that the entire
The system still works normally.
A wireless communication network with self-organization and self-healing capabilities is the most ideal communication method.
low cost
The complexity of the equipment is low, and the Zigbee protocol is royalty-free, which can effectively reduce equipment costs;
Zigbee’s working frequency band is flexible. It is 2.4GHz, which is a license-free frequency band, which is wireless communication without usage fees.
Large network capacity
A ZigBee network can accommodate up to 254 slave devices and a master device, and more than 200 ZigBee networks can exist in an area at the same time;
Data Security
ZigBee provides data integrity checking and authentication functions, the encryption algorithm adopts AES-128, and each application can
To flexibly determine its security attributes.
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