Serial RS232 and RS485 Connectivity - Problems and Solutions
The RS232 and RS485 serial port has its share of problems. Some of them are inherent while others arise during its usage. The intrinsic ones are constituted by its limitations, while the ones that occur when being used are spontaneous. This means that the RS232 / RS485 serial port has 'an already predicted' problem (the inherent ones) and problems that are unforeseeable. These unpredictable problems, however, occur very frequently and should therefore be seriously considered.
The most common problem, that happens to be a part of the RS232 and RS485 serial ports, is its mode of transmission. It can only send single bits of RS232 data which makes communication very slow. This can be a major problem, especially when its being used in a busy environment, and easily brings a lot of dissatisfaction. The good news is that this problem can be solved by the use of an intermediate RS232 / RS485 data link peripheral interface UART. UART (Universal Asynchronous Receiver-Transmitter) is an integrated circuit which contains software that converts single bit data format into 8-bit stream of parallel data. This enhances the speed of RS232 communication between two devices, and, in turn, facilitates the processing of RS232 data.
Another problem that is experienced by users of the RS232 / RS485 ports is the absence of flow control (hand shaking) or its misconnection. This usually results to communication lock-up or buffer overflows. These buffers are usually called FIFO because they occur in a first-in first-out mode. The only way to minimize this problem is by using UART. The UART has trigger levels which indicate the number of bytes of information that can be sent to it from the computer. The computer communicates with the UART devise and access the time that the buffers in it can be refilled. With good RS232 communication between these two (the computer and the UART) these buffer overflows can be greatly reduced. This relates to both RS232 and RS485.
The third problem, which is likely to be experienced, using RS232, is incorrect communication between DTE and DCE devices. This result in some handshaking lines or even the reversal of receives and transmits RS232 data lines. The RS 232 link cable between the two devices is usually the cause of this problem. The solution to this problem is to disconnect the RS232 cable until the problem is over. This is done because the problem might have arisen due to a wrong connection of the RS232 cable.
The fourth problem that is faced by many users of RS232 to RS485 ports is incorrect pin configuration, or finding it hard to deal with the serial ports' connector genders. This makes it hard for people to 'mate' or connect any devise that uses this kind of connecters. This is because some devises have 25 pins while others have 9 pins, some are male some are female. As a result, some people get frustrated with these devises and some end up not using them. To solve this problem, people can use intermediate cables such as RS232 DB9 gender changes or custom made cables. These cables help in connecting devises with different numbers of pins -on either the female or the male connector-and hence make it easier for the users.For further information regarding serial data communication please visit http://www.USconverters.com.
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