Using CitectSCADA > Communicating with I/O Devices > Setting Up Communications > Using a Serial Board
Using a Serial Board

The communications port on the computer is not designed for high-speed communications and reduces system performance. Instead, install a high-speed serial board (such as a Digiboard). High-speed serial boards have several ports (usually 4, 8, or 16) to let you connect several I/O Devices to your CitectSCADA system.

You can use identical I/O Devices or I/O Devices supplied by different manufacturers; CitectSCADA supports most popular I/O Devices. You can connect any number of I/O Devices; the only limitation is the size of your computer. High-speed serial boards are available for RS-232, RS-422, or RS-485 communication.

If you have several I/O Devices from the same manufacturer and these I/O Devices support multi-drop communication, you can connect them to an RS-422 or RS-485 high-speed serial board installed in your computer. (The RS-232 standard does not support multi-drop communication.)

Not every high-speed serial board supports RS-422. You can use an RS-232/RS-422 or RS-232/RS-485 converter to achieve the same arrangement.

Note: Using a converter can introduce handshaking/timing considerations.

To set up CitectSCADA to use a serial board:

  1. Install the board in your computer and set it up under Windows as per the accompanying instructions. Use the latest driver from the board manufacturer.
  2. Make sure that the boards configuration has COMx as the Type, and the Address set to 0. The I/O Port, Interrupt, and Special Opt can be left blank.
  3. Enter the Port Number in the Ports configuration. The COM port number is usually greater than 2 and set in the Ports section of the Control Panel. Use the Special Options field to modify the behavior of the COMx driver. (See COMx driver special options reference for more information).


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