Chapter 4. CPU Operation
GFK-2222AD
April 2018
149
4.5
Run/Stop Operations
The PACSystems CPUs support four RUN/STOP Modes of operation. You can change these modes in the
following ways: the RUN/STOP Switch, configuration from the programming software, LD function blocks,
and system calls from C applications. Switching to and from various modes can be restricted based on
privilege levels, position of the RUN/STOP Switch, passwords, etc.
Mode
Operation
Run/Outputs
Enabled
The CPU runs user programs and continually scans inputs and updates physical
outputs, including Genius and Ethernet outputs. The Controller and Backplane
Communications Windows are run in Limited, Run-to-Completion, or Constant
mode.
Run/Outputs
Disabled
The CPU runs user programs and continually scans inputs, but updates to physical
outputs, including Genius and Field Control, are not performed. Physical outputs are
held in their configured default state in this mode. The Controller and Backplane
Communications Windows are run in Limited, Run-to-Completion, or Constant
mode.
Stop/IO Scan
Enabled
The CPU does not run user programs, but the inputs and outputs are scanned. The
Controller and Backplane Communications Windows are run in Run-to-Completion
mode. The Background Window is limited to 10ms.
Stop/IO Scan
Disabled
The CPU does not run user programs, and the inputs and outputs are not scanned.
The Controller and Backplane Communications Windows are run in a Run-to-
Completion mode. The Background Window is limited to 10ms.
Note:
STOP Mode I/O scanning is always disabled for redundancy CPUs.
Note:
You cannot add to the size of %P and %L reference tables in RUN Mode unless the %P and
%L references are the first of their type in the block being stored or the block being stored is
a totally new block.
