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:
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