Change over between Master and
Slave board
Field Bulletin
Date: July 1, 1999
Products: SC3 Control Board
Subject: Change over between Master and Slave board
Author: Randy Rose
Although the SC3 chassis can function fully using
only one SC3 control card, it is preferred and recommended
that there be a redundant SC3 card plugged into the
secondary slot to prevent backup in the event of a
failure. When the redundant card is added to the system,
one card will run in master mode and the other in
slave mode. Both the SC3 Master and Slave cards are
completely updated with the current system configuration
including refreshes to all router levels and their
outputs as well as the mapping tables needed to continue
switching the various router configurations. This
allows for seamless operation if a switch from the
Master to the Slave is required. There are certain
precautions, which must be taken when manually forcing
a changeover between the master and slave boards to
avoid data loss or corruption. This document addresses
this area of the SC3.
Reset and Changeover Switch Functions
RESET SWITCH
The reset switch (SW1) is to be used after changing
the IP address or gateway address and/or enabling
any UDI or RMS ports all via the remote diagnostics
shell. This resets the controller with the new settings
and is performed by pressing the button. (Note: The
reset switch is NOT a default switch and will not
clear the SC3 cards current configurations.)
Results:
Master Reset Switch:
When pressed, LED's DS3-DS12, on the Master card,
will light while all other LED's are off. The Master
LED will then come back on after a couple of seconds.
The Slave LED on the redundant card will turn off
and then come back on after several seconds, indicating
it is ready. Actual time required for the Slave to
become ready is determined by the size of the system
configuration. Larger systems take longer. Note: Takes
will not be possible from any control panels during
the second or two it will take for the Master to be
reset and active again.
Slave Reset Switch:
When pressed, LED's DS3-DS12, on the Slave card, will
light while all other LED's are off. The Slave LED
on the redundant card will then come back on after
several seconds. Once again the time is determined
by the size of the system configuration. The Master
card and all of its LED's will remain unchanged. Operation
of the Master card is also unaffected.
CHANGEOVER SWITCH
The changeover switch (SW2) is used to force the
Master card into Slave mode, which causes the Slave
card to become the Master. (Note: Typically there
should be no reason to perform a changeover as both
cards are updated together and have the same configurations
within their memory). Redundancy is available for
backup use in case the Master card fails or becomes
corrupted. A changeover may be initiated if a hardware
failure is suspected on the current master card to
see if the redundant card exhibits the same symptoms.
Results:
Master Changeover Switch:
There are two LED's (one labeled Master and the other
labeled Slave) on each SC3 card and depending on which
one is the active (Master) card and which is the redundant
(Slave) card, determines which of the LED's are on.
Immediately after pushing the changeover switch on
the Master card, the Slave card should become the
new Master. However, the new Slave card DOES NOT become
active immediately and the period of time required
doing so will vary depending on the size of the system
configuration. When the changeover switch is pushed
to the left it will immediately transfer to the Slave
card, which will now have the Master LED lit. The
original Master card will then take several seconds
to establish itself as the Slave card and turn on
the Slave light.
Slave Changeover Switch:
The changeover switch is non-functional when a card
is in Slave mode.
Improper Changeover can cause Corruption
There is only one proper method that should be used
to change over from the Master card to the Slave card
so as to not lose any crucial data or corrupt any
files that reside in the SC3 cards. Pushing the changeover
switch (SW2) on the Master card to the left does this.
Preventative Measures against Corruption
DO NOT push
the changeover switch on the Master card if the redundant
(Slave) card is not ready. The Slave LED should be
lit on the redundant card. This indicates that it
is ready and active as the Slave card. (The changeover
switch is non-functional without a slave ready status.)
DO NOT push
the changeover switch interchangeably between the
Master and Slave cards without allowing the Slave
card to become ready. (Wait at least 5 seconds after
the slave is ready before forcing changeover again.)
DO NOT pull
the Master board out before the redundant (Slave)
card is ready. If this is done, then before reinstalling
the original Master card, pull the remaining card
from its slot and install the original Master card
prior to putting the Slave card back in.
Changing IP Settings in RMS
Each SC3 board has its own IP address assigned to
it for communications. RMS must be configured to address
the IP of the Master card to establish communications.
For smooth changeover from the Master card to the
Slave card it is recommended that the user first select
the IP address of the Slave card from the RMS application
before using the changeover switch located on the
Master SC3 card.
After the changeover is performed, RMS will then
be addressing the correct IP address. Clicking on
the dropdown menu labeled "Setting" and then selecting
"Remote Connection..." from the list does this. Type
in the IP address of the redundant card and click
the button labeled "Apply". Note: This may take several
seconds to occur. Immediately after this has been
done, push the changeover switch on the Master card
so the Slave board will become active and the RMS
application will perform an update of the new Master
card, reflecting an hourglass during this process.
More Information
If a changeover
is performed incorrectly and data is corrupted or
lost the different router and panel objects may need
to be setup again and individual files reloaded in
their respective locations. In some instances a complete
default of the SC3 cards may need to be performed.
For more detailed information regarding reloading
of configurations, see Field
Bulletin 114.
For a more complete
description on establishing communications, Ethernet
connections and setting up IP / Gateway addresses,
refer to Field Bulletin 113.
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