What You Should Have Asked Your Teachers About What Is Rs485 Cable > 자유게시판

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RS-485, like RS-422, can be made full-duplex by using four wires. Just like it’s older brother RS232, RS485 is a form of serial communication. RS-485 does not define a communication protocol; merely an electrical interface. The RS485 communication interface allows the slave unit (i.e. control module) to be interrogated and some options programmed by a remote computer. PTZ and camera zoom Could be controlled by RS485 and RJ45 network. PTZ Cameras are commonly used in applications such as surveillance, video conferencing, live production, lecture capture and distance learning. PTZ is an abbreviation for pan, tilt and zoom and reflects the movement options of the camera. Vehicle mounted camera solution can be deployed where a rapid security response is required. Support kinds of resolution IP camera max 2.0 megapixel. Although the devices would share the same network, communications would only be understandable by members of the same group. With your RS485 network, you can remotely monitor and control that pump from a control center. This makes utilizing RS485 simple. A simple network of a PLC, VFD, and an HMI allows remote control of motors in an industrial setting. Since it is differential, it resists electromagnetic interference from motors and welding equipment.

This allowed for electrical noise to cause interference. Termination resistors also reduce electrical noise sensitivity due to the lower impedance, and bias resistors are required. Another plus for RS485 is that it is less susceptible to noise issues. EIA-485 (formerly RS-485 or RS485) is a specification for the physical layer of a network that uses the difference in voltages between two wires (Three wire) to conveys data. It also defines three generator interface points (signal lines); A, B and C. The data is transmitted on A and B. C is a ground reference. There are three flag bits implemented in the SPSR (SPI status register). Any of these conditions may generate an interrupt if the SPIE (SPI interrupt enable) bit in the SPCR control register is set. The MODF bit is cleared by a read of the SPSR followed by a write to the SPCR. The SPIF is set when a data transfer is complete, and is cleared by a read of the SPSR status register, followed by a read or write to the SPDR data register.

WCOL is cleared by a read to the SPSR followed by a read or write to the SPDR. The received data byte is accessed by reading SPDR data register. A data transfer is initiated by a master device when it stores a message byte into its SPDR register. Any required SPI output signals must be configured as outputs, either by calling InitSPI() or by setting the appropriate bits in the Port D data direction register DDRD. This bit should be set only after all other SPI configuration is complete. Once the data has been exchanged, a flag bit in the SPSR status register is set to indicate that the transfer is complete. The WCOL flag is set when a write collision occurs. The data transfer that is in process when the write collision occurs is completed. A mode fault occurs when the SPI senses that a multimaster conflict (MC68HC11F1 Technical Data Manual, what is rs485 cable p.8-7) exists on the network as explained above in connection with the /SS input. The SPIE bit in the SPCR (SPI control register) enables SPI interrupt handling.

It is important to note that when the CPHA bit is 0, the /SS line must be de-asserted and re-asserted between each successive data byte exchange (68HC11 Reference Manual, Section 8.3.2). If the CPHA bit is 1, the /SS line may be tied low between successive transfers. Section 4 defines the electrical characteristics of the generator (transmitter or driver), receiver, transceiver, and system. This section also defines the logic states 1 (off) and 0 (on), by the polarity between A and B terminals. If A is negative with respect to B, the state is binary 1. The reversed polarity (A positive with respect to B) is binary 0. The standard does not assign any logic function to the two states. This function properly configures the directions of the SPI I/O pins, and configures the data transfer such that data is valid on the falling trailing edge of the clock, with the clock idling in the low state.