The RS-232-C standard specifies data rates of 50, 75, 100, 150, 300, 600, 1200, 2400, 4800, 9600, and 19200 baud per second. RS-232-C standard stipulates that the driver is allowed to have a capacitance load of 2500pF, and the communication distance will be limited by this capacitance. For example, if a communication cable with 150pF/m is used, the maximum communication distance is 15m; if the capacitance per meter of cable is reduced The communication distance can be increased. Another reason for the short transmission distance is that RS-232 is a single-ended signal transmission, which has common ground noise and cannot suppress common-mode interference. Therefore, it is generally used for communications within 20m.
RS-485 bus, widely used RS-485 serial bus standard when the communication distance is tens of meters to thousands of meters. RS-485 uses balanced transmission and differential reception, so it has the ability to suppress common-mode interference. In addition to the bus transceiver's high sensitivity, it can detect voltages as low as 200mV, so the transmitted signal can be recovered beyond a few kilometers. RS-485 uses a half-duplex mode of operation. Only one point can be in a transmission state at any time. Therefore, the transmission circuit must be controlled by an enable signal. RS-485 is very convenient for multi-point interconnections, eliminating many signal lines. Application of RS-485 can be networked to form a distributed system that allows up to 32 drives in parallel and 32 receivers.
RS422 bus, RS485 and RS422 circuit principle is basically the same, all are sent and received in differential mode, do not need digital ground. Differential operation is the fundamental reason for transmission distance far away from the same speed. This is the fundamental difference between the two and RS232, because RS232 is a single-ended input and output, and at least requires a digital ground transmission line and an acceptance line three lines for duplex operation. (Asynchronous transmission), you can also add other control lines to complete synchronization and other functions. RS422 through two pairs of twisted pair can work full duplex transceiver without affecting each other, and RS485 can only work in half duplex, can not send and receive simultaneously, but it only requires a pair of twisted pair.
RS422 and RS485 can transmit 1200 meters at 19kpbs. The device can be connected on the new transceiver line.
In the past, communication between PCs and smart devices mostly depended on RS232, RS485, Ethernet, etc., depending on the interface specifications of the device. However, RS232 and RS485 can only represent the physical media layer and the link layer of the communication. If you want to achieve two-way data access, you must write your own communication application program. However, most of these programs cannot meet the ISO/OSI specifications and can only be implemented. The single function is applicable to a single device type, and the program does not have versatility. In the equipment network of RS232 or RS485 equipment, if the number of equipment is more than two, RS485 must be used as the communication medium. RS485 network equipment only needs to transfer information through the "Master" equipment to realize the communication. The main equipment is usually a PC, and only one main equipment is allowed in this equipment network, and the rest are all slave devices. The fieldbus technology is based on the ISO/OSI model and has a complete software support system that can solve problems such as bus control, collision detection, and link maintenance.
Overhead sectional door most widely used for loading areas on all types of industrial premises and Designed with a curved overhead track, these vertically-opening sectional doors can be installed in areas with reduced head room. They provide heat and sound insulation with its composite panel construction.
The counterbalance and cable system provides quiet and straight forward operation for manual doors. Electric operation is available for larger applications that can incorporate many alternative operator options to suit all client requirements.
The standard outer panels are manufactured from 0.5mm thick, high quality zinc coating to BS EN 10147
For the best weather protection the sectional door panel has an interlocking hinged joint integrating a high quality seal the full length of the panel.
A counterbalance system is incorporated into the sectional overhead door to ensure efficient and effortless operation.
The counterbalance comprises of springs mounted on a steel shaft that are high tensile helical wound steel. It has been heat treated for enhanced performance for around 50,000 cycles.
Reducing shaft friction is achieved with the aid of brackets and guide rollers incorporating highest quality sealed bearings.
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