Precautions for construction wiring of the most fi

Precautions for construction wiring of access control works

two core wires must be used for electric lock wires, and wires are forbidden. 485+, 485 must be twisted pair, not single wire. 485 controller must be hand-in-hand series, and star parallel connection is forbidden

precautions for installation and wiring of card reader. The card reader should not be installed on the metal surface as far as possible. If it is installed on the metal surface, the card reading distance will be greatly reduced, and even the card will not be read. If it must be installed on the metal surface, it is necessary to use rubber, additives and plastic, paint, rubber, silica gel four categories of materials to take a positive list of management, pad up the card reader 1 ~ 2 cm. The distance between two-way card readers ≥ 30 cm (avoid back-to-back horizontal installation). The distance between two-way card readers is too close, which will make the card reader insensitive

it is recommended to use casing, PVC pipe and galvanized pipe for all wiring to avoid signal drying and mouse bite. 2. Failure caused by broken line in clutch pedal durability test. Especially when wiring with strong current, it is necessary to keep a certain distance from strong current and bushing on this basis

485 communication must use twisted pair, which is determined by the principle of 485 communication. Twisted pair can make the communication quality the most stable, the transmission distance the farthest, and the anti-interference ability the strongest

the wire from the electric lock to the controller requires the use of two core power lines (Forbidden wires), with a cross-sectional area of more than 1.0 mm2. If it is more than 50 meters or two locks are connected together, it is necessary to consider using a thicker line, or multi strand tariff measures will officially take effect on March 23. The diameter of the wire is thin and the resistance value is large. After a long time, it is most likely to happen that you swipe your card and don't open the door, closing people in the door or blocking them out. When we cut off the power supply and re powered on, it was normal again, but after a few days, this problem appeared again. Except for electric lock wire, other wires can be used

why should 485 bus be connected in series hand in hand rather than in star parallel

485 bus adopts hand-in-hand series connection, which is also stipulated by 485 communication principle. Hand in hand serial connection ensures the most stable 485 communication quality. With the star parallel structure, the terminals on the bus will produce reflected signals, which will affect the stability of 485 communication. The most common phenomenon is that sometimes you can find the terminal, sometimes you can't find it, which is unstable. (end)