There are a variety of Ethernet temperature and humidity sensors on the market, which are mixed with fish and dragon. Confused, what type of sensor should I choose? ? The author summarizes the following points based on actual tests, on-site understanding and other aspects for selection, for the reference of engineers:
1. Professional, depends on whether a company is professional, depends on the company's position in the industry and whether the equipment is advanced, whether it has made achievements in the technical field. Technically, they are relatively mature.
Humidity measurement is not simply a technical issue. As a composite technology of electronic technology and physical chemistry, experience is very important, and ignorant people are not afraid. Not all electronic engineers understand this, especially the design of production processes. Making a product is different from producing a product.
Therefore, unlike the cottage collection, it is more secure to choose a historical and professional company. After all, these sensors are not bought for our own use, but for customers. Quality assurance is very important.
2. Equipment, temperature and humidity sensors have accuracy requirements. It is very important to have relevant calibration equipment to calibrate the products before leaving the factory. It is either the accuracy of the device or the accuracy of the finished product. A high-precision humidity environment is expensive, and it is calibrated with the national standard measurement and obtained a calibration certificate every year. These must be clearly investigated with the manufacturer. 3% product accuracy, at least 1% of equipment can be guaranteed.
3. Volume, the production volume of the product is very important. If the product does not have a batch, then the reliability of the device is not guaranteed. It is important to know that IC manufacturers generally do not accept small batch orders, and cheap old ICs and refurbished ICs in the electronics market are the mainstream. . This is also the reason for the unstable product quality of some small factories.
The simple way to judge the batch size of a product is to look at the general-purpose shell used in the product's shell or the shell dedicated to mold opening. Usually only the mass-produced products will open the mold.
4. Security, threatened everywhere in the network field. Data security issues are very important. At present, most manufacturers choose integrated protocol products for the Ethernet interface. However, these integrated modules are usually used in commercial occasions. The factory settings are made in the most convenient way. The security is not enough, and it is easy to be modified and attacked by the network. I have had this kind of product and used it in the public network. After 2 ~ 3 months, the network parameters have been modified and learned. Therefore, professional manufacturers generally reprocess this and rewrite the underlying programs to enhance their security.
5. Shape design, usually the author likes to choose products that meet the standards. For example, there are usually 86 junction boxes on site, and products with the same size are easy to install. Pluggable terminals or connectors are very important, otherwise the wiring for construction and maintenance in the future will be a very painful thing. These details reflect the degree of intention of the manufacturer on the product. As far as beauty is concerned, it's a matter of opinion. I prefer small products.
6. Function, the key to understanding what you need is the sensor. Many products now have some additional functions that actually affect accuracy. Moreover, it is troublesome and unsightly to connect so many wires to one sensor.
Small computer system interface (SCSI) is an independent processor standard for system level interfaces between computers and intelligent devices (hard disks, floppy drives, optical drives, printers, scanners, etc.). SCSI is an intelligent universal interface standard.
1. SCSI can support multiple devices, SCSI-2 (fastscsi) can connect up to 7 SCSI devices, and widescsi-2 can connect 15 SCSI devices. In other words, all devices only need to occupy one IRQ. At the same time, SCSI also supports a wide range of devices, such as CD-ROM, DVD, CDR, hard disk, tape drive, scanner, etc.
2. SCSI also allows one device to transfer data and another device to look up its data. This can achieve higher performance in multitasking operating systems such as Linux and windows NT.
3. SCSI occupies a very low CPU, so it has obvious advantages in multitask system. Since the SCSI card itself has a CPU, it can handle all the transactions of SCSI devices. When the host CPU sends work instructions to the SCSI card, the SCSI card will work by itself. After the work is finished, the work results will be returned to the CPU. In the whole process, the CPU can carry out its own work.
4. The SCSI device is also intelligent. The SCSI card can queue CPU instructions by itself, which improves the work efficiency. In multitasking, the hard disk will be in the current head position, and the adjacent tasks will be completed first and then processed one by one.
5. The fastest SCSI bus has a bandwidth of 160MB / s, which requires the use of a 64 bit 66MHz PCI slot. Therefore, the maximum speed that can be achieved in the PCI-X bus standard is 80mb / s. if it is used with a dedicated hard disk with 10000rpm or 15000rpm, it will bring obvious performance improvement.
SCSI-180°DIP Section
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