RS485 Standard – Classes Discovered From Google > 자유게시판

Then the annex states that consideration should be given to various things including grounding arrangements. Many industrial equipment, including PLC, DCS, smart meters, etc., are using Modbus protocol as the communication standard between them. RS232 is one of the mainstream serial communication interfaces. RS485 is a serial communication protocol that is commonly used in industrial applications. The RS232 interface conforms to the serial data communication interface standard established by the Electronic Industries Alliance (EIA) of the United States. The standard value of the maximum transmission distance is 50 feet. The RS232 transmission distance is short (the maximum transmission distance standard value is 15 meters), and the RS485 transmission distance is longer (the maximum transmission distance is 1200 meters). 3) The standard value of the maximum transmission distance of the RS485 interface is 4000 feet, which can actually reach 3000 meters. 200V AC doesn't reach the signal transformer. In the straight cable, all noise current is flowing in the same direction, practically generating a looping current just like in an ordinary transformer. When the cable is twisted, we see that in some parts of the signal lines the direction of the noise current is the oposite from the current in other parts of the cable.

Pull a cable between the two devices and see if they can talk to each other. 6V, and logic "0" is represented by the voltage difference between the two wires -6V to -2V. 3V as logic "0", signals lower than -3V as logic "1", TTL level of 5V is logic positive, and 0 is logic negative. The ground signal is a common return for all signals. 3) The interface uses a signal line and a signal return line to form a common ground transmission form. The transmitter and receiver compare the voltages of the data- and handshake lines with one common zero line. With RS485 on the contrary there is no such thing as a common zero as a signal reference. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. However, the UDP protocol cannot guarantee that data will not be lost, and it is easy to cause error codes.

Several volts difference in the ground level of the RS485 transmitter and receiver does not cause any problems. Sig- line. The RS485 receiver compares the voltage difference between both lines, instead of the absolute voltage level on a signal line. For example: An RS-422 network has an always active driver and receiver. Since data rates on a PC serial port can vary from 300 baud (26mS for 8-bits) up to over 100k baud (0.08mS for 8-bits), the timer will have to either be limited in the baud rates that it can work with, or keep control of the RS-485 network for much longer than it needs. It supports maximum data rates at a length of 1200 meters, making the RS485 protocol an excellent choice for communication between physically distant pieces of equipment. RS232, RS422, RS423 and RS485 are serial communication methods for computers and devices. But actually there are only two gaps - two gaps are enough to make the three ports isolated from each other. The third installation uses the same two computers as the second example, but they are separated by several thousand feet of wire, and one of the computers is sitting next to an arc furnace that draws several thousand amps when operating.

The modem may be limited to half-duplex communications, and therefore the link between the two computers is half-duplex. Earth isolation is expensive, may require purchasing of additional isolated PSU's (where you already have a grounded PSU from the vendor), or purchasing of addon isolated bus transceivers (when you already have a non-isolated port on your device, chosen for other reasons). The RS485 transceivers are balanced, RS485 standard but work with a permanent DC offset of something over 2 Volts. All of the drivers and transceivers must be able to be "made passive" or effectively disconnected from the network to allow other drivers to transmit. The TCP/IP protocol must belong to the network layer and the transport layer. If divided into ISO's 7-layer model (physical layer, data link layer, network layer, transport layer, session layer, presentation layer, application layer), the serial port actually only includes the physical layer and data link layer. The IP Filter section is used for configuring which network is allowed to communicate with the device.