GE Energy
D20/D200
Installation and Operations Guide
General 994-0078-2.00-7
Full
83
Connections and Configuration, continued
Redundant
D20/D200
Systems
To implement a redundant D20/D200 system, you need:
• A second CCU, built and configured the same as the first CCU
• RS-232 Switch Panel(s)
• Two RS-232 Switch Panel Monitor and Control cables, referred to as Watchdog
cables, connecting each CCU to the RS-232 Switch Panel. Refer to “Procedure:
Installing Watchdog Cable
s” on page 85 for details.
• One inter-CCU co
mmunications cable, providing either a Ping connection, or a
(D.20) HDLC connection, between CCUs A and B. The method used depends on
the availability of serial and D.20 ports. As appropriate, refer to:
− “Procedure: Installing a Ping Cable” on page 85
− “Procedure: Installing an HDLC Cable” on page 86.
• Serial co
mmunication cables. The number of serial cables depends on your
system configuration. Serial connections from CCUs to your field equipment are
cabled and switched through the RS-232 Switch Panel. The RS-232 Switch
Panel switches up to eight communications links to the Standby CCU, in the
event of a failure of the Active CCU. See “Procedure: Connecting Serial
Co
mmuni-cation Cables” on page 86 for details.
Note:
Refer to “Required Components” on page 84 for component part numbers
and functio
ns.
Note: Refer to “
D20/D200 Redundancy” on page 39 for a description of
D20/D200 redundancy.
Note: The RS-232 Switch Panel is not equipped with EMI protection
circuitry. If the connection length exceeds 3m, a Serial Surge
Protection Panel (GE item number 540-0249) or equivalent protection
device should be installed.
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