Chapter 4. CPU Operation
GFK-2222AD
April 2018
151
STOP-Halt Mode
Following an internal fault, such as a hardware watchdog timeout or an ECC Memory Check fault, the
CPU will automatically go into STOP-Halt mode. In this mode, logic execution and I/O scanning is
suspended.
Depending on the underlying cause, CPU rack backplane communications may also be suspended. For
example, following a hardware watchdog timeout, the CPU restarts in STOP-Halt mode with backplane
communications operational. In contrast, following an ECC Memory Check Fault, the CPU immediately
enters STOP-Halt mode with backplane communications suspended.
To recover from STOP-Halt mode, the CPU/CPE must be disconnected from its backup power source
(battery or Energy Pack), powered off, then powered back on, after which the backup power source
should be reconnected.
To enable backplane communications where they have been disabled in STOP-Halt mode, cycle power
with its backup power source attached (battery or Energy Pack), then powered back on.
While the CPU is in STOP-Halt mode, the PACS Analyzer tool may be employed to examine
the CPU’s
fault tables. The PACS Analyzer software is a tool that is embedded in PME. It can also be downloaded
from the GE Automation and Controls support website
If backplane communications have been suspended, the PACS Analyzer must be directly connected to a
serial or Ethernet port on the CPU. If backplane communications are operational, the PACS Analyzer may
be connected via a communications or Ethernet module in the backplane, or to a CPU-embedded port.
RX3i CPE302/CPE305/CPE310/CPE330/CPE400 and RSTi-EP CPE100/CPE115 CPU models only:
The programmer can connect to these CPUs in STOP-Halt mode through the embedded Ethernet port
without a reset or power cycle.
STOP-Fault Mode
In STOP-Fault Mode, logic execution and I/O Scanning cease after the number of last scans (configured
by the user) has been exhausted. Client communications also cease at that time. Server communications
are available, but with PLC data which has become static.
Within PME, the user can configure each fault action to be either
diagnostic
or
fatal
.
•
A diagnostic fault does not stop the Controller from executing logic. It sets a diagnostic variable
and is logged in a fault table.
•
A fatal fault transitions the Controller to the STOP-Fault Mode. It also sets a diagnostic variable
and is logged in a fault table.
Within PME, the user can also configure the number of last scans to be executed in the event of a fault
(see PME
Scans
tab,
Number of Last Scans
parameter).
To recover from STOP-Fault Mode, resolve the underlying cause and clear the Controller Fault Table. This
allows the CPU to transition to STOP-I/O Disabled Mode.
