315MHZ and 433MHZ are our country's application-free launch receiving frequency. 433MB is an old product in the field of data transmission. There is a huge hidden danger for data transmission: 433 megabit system, its fatal weakness is poor system security, it is easy to be Attacks, deciphered; communications technology is backward, communications are not reliable, the system is unstable; the channel is very congested, the environment is particularly disturbing, intercoms, vehicle-mounted communications equipment, amateur communications equipment, etc., are concentrated here, so the environmental interference is very large; short-term use It may not be obvious that long-term use will definitely show up; in addition, the power consumption is large, and the transmitter and antenna are bulky. Some manufacturers introduce it into smart home systems. However, due to their weak anti-interference ability, inconvenience in networking, and reliability, the smart home The application effect is unsatisfactory.
ZigBee is a short-distance, simple architecture, low power consumption and low transmission rate wireless communication technology. Its transmission distance is about tens of meters, the use of the frequency band is free of 2.4GHz and 900MHz frequency band, the transmission rate is 20K to 250Kbps, The network architecture has Master/Slave properties and can achieve bidirectional communication
ZigBee has the following features
(1) Power saving: ZigBee has a low transmission rate, and it also has a small amount of data transmission. Therefore, the time for sending and receiving signals is short. Secondly, in non-working mode, ZigBee is in sleep mode, and the time between work and sleep modes is changed. Normal sleep activation time is only 15ms, and device search time is 30ms. Through the above methods, ZigBee is very energy-efficient, and ZigBee can support the use of ZigBee for up to 6 months to 2 years.
(2) High reliability: The MAC layer of ZigBee adopts a talk-when-ready collision avoidance mechanism. This mechanism is immediately transmitted when there is a data transmission request. Each data packet transmitted is received and confirmed by the receiver. The confirmation message is returned. If there is no reply from the confirmation message, it means that a collision has occurred and will be transmitted again. In this way, the reliability of the system information transmission is greatly improved.
(3) High scalability: A ZigBee network includes a maximum of 255 ZigBee network nodes, one of which is a Master device, and the rest are Slave devices. If using Network Coordinator, the overall network can reach up to 6500 ZigBee network nodes. In addition, each Network Coordinator can be connected to each other, and the overall number of ZigBee network nodes will be considerable.
IOT Sensing---Xue Hui 025-52260017
Lab Syringe Pump for microinjection, microfluidics, perfusion, and other lab microinjection applications.
We support 1 syringe or 2 syringes pump. Suitable for the different work requirements.
The syringe pump is suitable for high-pressure and high-precision applications, such as high-performance liquid chromatography.
Lab Syringe Pump,Electrospinning Syringe Pump,Automatic Lab Syringe Pump,High Voltage Syringe Pump
Baoding Chuangrui Precision Pump Co., Ltd. , https://www.chuangruipump.com