Access control system product selection and construction points

Now that the access control system has penetrated into people's lives, the installation and application of access control systems are becoming more and more extensive. But the construction and wiring of the access control system need to pay attention to what you know? Here are a few of the big mistakes in the construction and wiring of the access control system.

First, use the network cable to electrically lock the cable to the controller

A section of the line from the electric lock to the controller in the construction of the access control looks very ordinary. If it is not standardized, it is easy to cause a fault phenomenon that is not easy to find the cause. This must be taken seriously!

Since the electric lock has a relatively large operating current (relative to other devices of the access control system such as the controller card reader), the electric lock has a certain distance from the controller, and the voltage drop on the line is relatively large. If the pressure drop is too large, the electric lock will sometimes be carried, sometimes with no movement. Magnetic locks sometimes have insufficient suction. The performance of the door switch is not normal. It will even grab the current resources with the controller, making the controller power shortage, restarting or even crashing.

Some engineers have convenient wiring at the moment, or easy to purchase. It is easy to cause troubles when using the network cable to electrically lock the wires to the controller. Although it seems that there is no problem during debugging, after a while, problems often occur. .

From the electric lock to the controller line, if the line length is less than 50 meters, it is required to use a two-core power line with a cross-sectional area of ​​1.0 square millimeter, without shielding. If it exceeds 50 meters, please double the cloth with a two-core power line and supply power in parallel. If the line length is greater than 100 meters, it is recommended to move the controller closer to the position of the door lock to shorten the wiring distance.

The cross-sectional area of ​​the network cable is 0.2 square millimeters, which is 5 times smaller than our standard wire, so it is absolutely impossible, even if the controller is close to the electric lock. The electric lock door magnetic signal line can be a network cable. Some people, the four shares of the network cable, to power the electric lock, although theoretically close to the norm, but it is not recommended. Doing so will make the terminals unstable.

Second, the power load is too large load

The standard configuration power supply is a 12V, 4A switching power supply. He can meet the power supply of up to four doors (5 electric plug locks or 4 magnetic locks) under the premise of wiring specifications and thick cross-sectional area. A shuang open door magnetic lock is the power of two single-door magnetic locks. If the system exceeds this configuration, for example: more than 5 electric plugs or more than 4 magnetic locks need to add a power supply and the original power distribution.

Note: If some of the electric lock power is too large, the power supply will be weaker.

If the power is not enough, it will not be shown when debugging, unless it is not enough. It appears that sometimes the door is locked, sometimes it can't be locked, and even the controller can grab current, causing the controller to restart or even crash.

Third, 485 bus system networking considerations

The 485 line does not use twisted pair or use a low-end passive converter! The 485 communication line cannot be star-connected and must follow the standard hand-held bus mode.

If the 485 trace is not standardized or exceeds the communication range, there will be a phenomenon that communication is not possible or sometimes communication is not possible.

485 transmission is a differential mode transmission mode. Only 485+ and 485- are twisted pairs, which can make the 485 transmission mode suffer the least interference, the transmission is the farthest, and the transmission quality is good. Some engineering companies do not use twisted pairs, which will make the interference very large. Some engineers mistakenly think that the transmission quality of the line will be better, the twisted pair will be synthesized, and the other twisted pair will be combined. This is counterproductive. Instead, the quality of communication is greatly reduced.

There is a small converter on the market that does not have a power supply, which is cheap. However, the anti-interference performance is not good, and it is generally used for indoor short-distance communication of a single machine, such as an attendance machine. Not suitable for access control systems. Although it claims to be able to carry 32 devices and has a transmission distance of 1000 meters, it is often far from the target in practical applications. So it is recommended that you do not use this passive converter. Unless it is indoors, the communication distance is less than 100 meters, and the number of loads is less than 2, which can be considered from the perspective of cost. Otherwise, it is highly recommended that you use an active 485 converter that is not expensive and much more stable. The number of load controllers is also large. Anti-interference, lightning protection, anti-surge effect is also very good.

The 485 wiring prohibits the star connection, that is, it cannot be pulled from the converter to each controller separately, and then connected in parallel on the converter. This connection makes the communication quality very poor. Be sure to come out of the converter, first to a controller, and then to the next control, one after another, like a string of grasshoppers.

Non-standard 485 wiring, even if it is improved with shielded grounding terminal resistors in the future will not help.

The future development trend is that TCP/IP networking mode replaces RS485 networking mode, TCP/IP networking is more stable, and compatibility and scalability are better.

Fourth, simply look at the access control system before the construction

Without consulting and understanding, you can connect some non-access control systems (such as automatic doors or elevators); each external device, even different manufacturers of the same equipment, have different electrical characteristics, if you are not familiar with these features It is easy to cause instability of the access control system, and a lot of interference, so please communicate with the technical staff of the access control factory before the external equipment, gain some experience, and also strengthen the familiarity of the electrical performance of the external equipment. And the improvement and precipitation of the engineer's own technical experience.

Fifth, construction standards are the key

When the customer sometimes refers to replacing the product with other products, the line is already laid, and when the line cannot meet the specification requirements, the line must be re-arranged, and the standard cannot be used. Nowadays, if you save trouble or luck, it will inevitably cost a lot of money and energy for future work.

Sixth, product selection

The electric lock that is disabled by the door is an important part of the access control system. It is the actuator and key equipment of the access control system. If the access control system is compared to a person, the electric lock is like the human hand and foot. It is related to the stability of the entire access control system. Sex. If an access control system controller and card reader are good, if the quality of the electric lock is problematic, it will also cause the door to open, which will affect the acceptance and use of the project.

Note 1: Is the purchase of domestic electric lock or imported electric lock?

Imported electric locks are too expensive, the purchase price must be more than 1,000 pieces, and there are no two thousand pieces to sell to users. Although the real import electric locks are mature, the repair rate of products is low, but the service is still a problem. Once there is a problem, foreigners can't move and say that China's power is unstable and many other reasons, it is very troublesome. I suggest to buy domestic locks, the price is very affordable, and most of them are produced in Taiwan or integrated into Taiwan. Process (Taiwan is the main OEM base for foreign electric locks) and quality standards, the difference is not much worse.

Note 2: Is it an electric lock or an electric lock?

What kind of lock should be matched, depending on what kind of door you are. shuang open (can be opened inside or outside) glass door as far as possible with electric lock, the company's internal single open (can only open inside or only open The wooden door is magnetic lock as much as possible, and the magnetic lock has the electromagnetic lock. The magnetic lock lock is installed on the upper part of the door frame. Some people will not think that it is not hidden and not beautiful. In fact, it is used abroad, and the use of foreign magnetic locks is required. Excess electric plug lock, the stability of the magnetic lock is also higher than the electric lock, but the safety of the electric lock is high. The electric lock is installed on the door side and the mechanical lock such as the ball lock, the safety is low. A lot, and the wiring is not convenient, but the price is cheaper, it is not recommended to adopt, the community is to buy magnetic lock and electric lock as much as possible, the electric control lock is relatively loud, the general building intercom is equipped with electric lock, now also A kind of silent electric lock can be considered. However, no matter what lock you use, you should pay attention to rain protection. The lock is made of iron and it is easy to rust. This should be noted. There are many other electric locks that are not popular. Not recommended because of limited production scale There are too few application cases, the products are immature, and the use is as little as possible. For example, there is a power-off lock on the market. This lock can meet the requirements of the customer after the power failure, but the door is still closed, but it does not meet the fire protection requirements. It is not acceptable, and it has a requirement for the thickness of the door frame. It will have unexpected troubles when installed, so it is recommended to be less recommended to customers.

Note 3: Is it purchased from the lock factory or purchased from the equipment supplier?

Buying electric locks directly from the lock factory may be cheap, but the quantity you purchase is limited, and you may not get good prices and services. There is also an access control system controller. You can find a company to buy, and the electric lock can be bought by a company. If the problem is shirked, it is not easy to deal with it. It is better to buy it from the controller supplier. The controller manufacturer and supplier generally do not directly produce the electric lock, because the electric lock manufacturing industry does not belong to the electronics industry, but belongs to the machinery. In the processing industry, they generally assess the quality of the locks of each lock factory through testing and trial use. If it is good, controller manufacturers generally use the OEM method to sell, and the brand of their own company, indicating the quality of the product. Be responsible for.

Note 4: Basic purchase knowledge of electric lock

First of all, the lock surface should have a metallic luster, and there must be no obvious scratches. The standby current is about 300 mA, and the operating current is lower than 900 mA. After a long time of power-on, the surface is slightly hot, but it is not hot. The force of the electric lock is required. Full, after the pressure is pressed, the lock can automatically bounce and be powerful. Try to perform 4000 times of continuity test. If it is found that the lock is weak during the process, or the bounce is not in place, or can not be lifted, it is considered unqualified. Some works Q: Is it a two-line or multi-wire electric plug lock? This is the case. The multi-wire electric plug lock is controlled by a single-chip microcomputer. The operating current of the electric lock is controlled by the single-chip microcomputer, and the lock body is not too hot. It also has a delay control function and a door magnetic detection function. The delay control function can be used for the door with a bad spring. The magnetic door monitoring function can provide the controller with real-time monitoring of the door opening and closing state. Although these functions may not be necessary for you. Used, but the quality and stability of the electric lock with MCU control and the electric lock without MCU control are not at one level. So it is recommended that you do not have to save a little money. The two-wire electric plug lock, the internal structure is not Simple, just a current driven solenoid mechanism, working current, severe fever to a certain time will damage the lock. Not recommended.

Note 5: Basic purchase knowledge of electromagnetic lock

The appearance should be exquisite, the surface should not have obvious scratches or rust. The key of the magnetic lock is to look at his tensile strength. This requires professional equipment to be measured, so only after installation, the hand pulls a sudden force. It is normal to pull it off, but it should be noted that the installation of the electromagnetic lock body should be consistent, and the suction iron should not be installed too tightly, otherwise it will affect the tensile strength.