CHAPTER 5: SYSTEM MAINTENANCE
SNAP PAC Redundancy Option User’s Guide
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Status messages for the arbiter include Connected, Trying to connect, and Not connected.
Status messages for the controllers include:
Message
Description
Active
The controller has a strategy and is able to run it. The strategy may or may
not be running at the moment.
Active (I/O Impaired)
The controller has a strategy and is able to run it. However, one or more
I/O units failed to respond to the controller's communication request within
the allowed time. You should verify that all I/O units are online. If that
doesn't resolve the issue, you can increase the arbiter's loop time by set-
ting its value in the memory map (arbiter MMP address 0xF8000104). The
default value is 50 milliseconds (00000032 hex) and the maximum value is
250 milliseconds (000000FA hex).
Cold Start
The controller is changing to active. This is usually a very short state.
Failed
The controller is not responding to the arbiter. It may be off, or discon-
nected, or have firmware or hardware issues.
Failed (Possibly Active)
The controller is not responding to the arbiter. Its last known state was
Active, and it may still be running its strategy.
Failover Start
The backup is changing to active and starting in the state of the previously
active controller.
Maintenance
Used for certain operations, such as download a strategy or installing firm-
ware.
Non-Qualified Backup
The controller is attempting to become qualified (copying firmware, strat-
egy, and chart state from the active controller). This state occurs fre-
quently, and it can take a while to complete everything. This message may
also indicate that the backup controller cannot communicate with the
I/O.
Online (Candidate)
Controller has a strategy and may become active. Usually a very short
state.
Online (non-candidate)
The controller has no strategy.
Powerup
A controller enters this state when it is first turned on.
Qualified Backup (Connected)
The controller is a qualified backup (ready to become active).
Qualified Backup (Disconnected)
The controller is a qualified backup but is not currently connected to the
active controller.
Update Complete
Used when a controller is coming out of Maintenance mode with a strategy
loaded and is attempting to become active. This is usually a very short
state.
Using the Memory Map to Read Status Messages
To see the status of a redundant controller in PAC Display, use the PAC Control command
Read
Number from I/O Unit Memory Map with the memory map address 0xF8001000. By frequently
reading the value in an I/O unit’s memory map and putting it into a variable, you can display the
status in PAC Display.
The value returned indicates the redundant controller’s status, as follows:
State
Value (Decimal)
Powerup
1
