GE D20MX, Руководство пользователя

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CHAPTER 3: CONNECTING TO DEVICES AND NETWORKS
D20MX HARDWARE USER’S MANUAL GE INFORMATION 43
To provide higher EMC immunity and maintain CE Mark radiated emission compliance, the
serial cables used for permanent serial and D.20 Link connections must comply with the
following requirements:
•
Cables must be shielded
• D-type connector covers must provide EMC shielding (e.g. metallized plastic or die cast
metal covers).
Serial
Seven serial communications ports are brought out to the backplane connector P2. These
serial ports are five-signal (TXD, RXD, RTS#, CTS#, DCD#) DTE serial ports, compliant to
ANSI/TIA-232 and TIA/EIA-694 specifications and are hosted by UARTs.
The D20MX is tested with all 7 serial ports running at 19200 baud with 20% CPU utilization.
Refer to application configuration guides for supported baud rates and for data bits.
To avoid burning out the WESTERM or D20MX mainboard when directly connecting a rear-
panel serial port on one D20MX chassis to another rear-panel serial port on any type of
D20 chassis, jumper the WESTERM of both chassis' to not provide a power connection to
pin 4. Refer to the appropriate WESTERM module layout for jumper settings.
D.20 Link
Communications between the D20 and the D20 peripheral I/O modules are carried over a
high-speed, high-level data link control (HDLC) protocol called the D.20 Link. The D.20 Link
has the following features:
•
RS-485 serial link, half duplex, 250 kbps
• D.20 frame using HDLC protocol format with Manchester encoding
• Supports up to 38 D20 I/O peripheral modules in a standard configuration