Rs-232; D20 System Redundancy - GE D20MX User Manual

CHAPTER 3: CONNECTING TO DEVICES AND NETWORKS

RS-232

Non-responsive
RS-232 port

D20 system redundancy

D20MX HARDWARE USER'S MANUAL
The RS-232 port on the D20MX is used to access the WESMAINT II+ facility and to transfer
code and configuration data to the D20MX. You can use a VT100-compatible terminal or
terminal emulation program to directly access the WESMAINT II+ facility. SGConfig's
Terminal Emulator is an example of a suitable terminal emulation program.
The RS-232 port is connected to the D20MX front panel and is also routed to the rear panel
as (COM0). The default baud rate is 19,200.
In the event that the D20MX RS-232 port appears non-responsive, type Ctrl-Q. This non-
responsive condition might occur if your computer goes into sleep mode and then wakes
up while still connected to the D20MX RS-232 port.
Use only a NULL modem cable (GE Energy part number 977-0529) when you are
connecting to the D20MX front-panel RS-232 connector. Use of a WESMAINT cable will not
allow communication to the D20MX.
Use only a standard WESMAINT cable (GE Energy part number 977-0300) when connecting
to the rear panel COM0 connector. Use of a NULL modem cable will cause permanent
damage to the D20MX and PC.
A redundant D20 setup allows a secondary D20 to automatically take over operations
from a paired D20 unit that has failed.
D20 equipment redundancy requires:
• Two D20 units and
• One or two RS-232 switch panels.
The quiescent current of the +12 V power supply input on the RS-232 Switch Panel is 15
mA. The maximum power requirement on the +12 V input during operation is 230 mA.
Through a toggle switch on the RS-232 Switch Panel, you designate one of the CCUs as the
Active unit. If the Active unit hardware or software fails, the Active CCU is automatically
switched offline, and the Standby unit is switched through to the field equipment (i.e., it is
made Active).
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.
Figure 19 shows a redundant D20 system, with CCU A active.
GE INFORMATION 49