• RS-485 serial port can communicate packets of data over a large network.computer image by peter Hires Images from Fotolia.com
  
  RS-485 transmission is a standard for drivers and receivers for use in balanced digital multiplex systems. The standard is published by the ANSI Telecommunications Industry Association/Electronic Industries Alliance (TIA/EIA). RS-485 technology can be used over long distances while minimizing electrical line feedback. However, problems can occur with RS485 serial port transmissions which can be corrected by troubleshooting the problem in several areas.
  
  

Transmission Modes

• RS485 serial ports can have problems concerning mode of transmission. The RS485 serial port can send single bits of data which make the computer system slow. In a business environment, this problem can cost time and on a large network, can slow down the access to software programs. The problem can be solved by using a UART (Universal Asynchronous Receiver-Transmitter) which is an integrated circuit containing software which converts single bit data format into 8-bit streams of parallel data. This enhances the speed of the RS485 serial port.
  
  

Connectivity

• As with most serial port configurations, RS485 can experience misconnections to other computer devices or have "handshaking" problems (connectivity to another device or peripheral). This problem usually results in computer system lock up or buffer problems. Again, the use of UART (Universal Asynchronous Receiver-Transmitter) can solve this problem by indicating the number of bytes of information that can be sent to it from the computer. UART can transform information into 8 bit data to control buffer overrun and system lock up.
  
  

Data Transfer

• Another major problem is the incorrect communication between DTE and DCE devices using the RS485 serial cable. This results in computer connection problems and slow data transfer. The RS485 link cable between the two devices is usually the cause of this problem. The solution to this problem is to test the cable to see if it needs to be replaced with a new RS485 cable and connector.
  
  

Connector Configuration

• Incorrect pin configuration can cause connectivity problems if the connectors are not compatible. Typically, some computer connectors have 25 pins while others have 9 pins. Some connectors are male while others are female. To solve this problem, use cables such as RS485 DB9 gender changes or develop custom made cables with a cable kit. These cables can assist in connecting devices with different numbers of pins regardless of female or male connector configuration and make data flow easier through the RS485 connector.