Cpu Stop Modes - GE VersaMax PLC User Manual

7.3 CPU Stop Modes

98 GFK-1503E
For public disclosure
7.2.3.1 Changing the Configured Default for Constant Sweep
Mode
If the PLC is in STOP mode, its Configured Constant Sweep mode can be edited. After
this is done, the configuration must be Stored to the CPU for the change to take effect.
Once stored, Constant Sweep Time mode becomes the default sweep mode.
7.2.3.2 The Constant Sweep Timer
During operation in Constant Sweep Time mode, the CPU's Constant Sweep Timer
controls the length of the sweep. The timer length can be 5 to 500 milliseconds. The time
should be at least 10 milliseconds longer than the CPU's sweep time when it is in
Standard Sweep mode, to prevent extraneous oversweep faults.
If the Constant Sweep Timer expires before the sweep completes, the CPU still completes
the entire sweep, including the windows. However, it automatically provides notice when
a too-long sweep has occurred. On the next sweep after the oversweep, the CPU places an
oversweep alarm in the PLC fault table. Then, at the beginning of the following sweep,
the CPU sets the OV_SWP fault contact (%SA0002). The CPU automatically resets the
OV_SWP contact when the sweep time no longer exceeds the Constant Sweep Timer. The
CPU also resets the OV_SWP contact if it is not in Constant Sweep Time mode.
As with other fault contacts, the application program can monitor this contact to keep
informed about the occurrence of oversweep conditions.
7.2.3.3 Enabling/Disabling Constant Sweep Time, Reading or
Setting the Length of the Timer
SVCREQ 1 can be included in the application program to enable or disable Constant
Sweep Time mode, change the length of the Constant Sweep Time, read whether Constant
Sweep Time is currently enabled, or read the Constant Sweep Time length.
The PLC may also be in either of two Stop modes:
• Stop with I/O Disabled mode
• Stop with I/O Enabled mode
When the PLC is in Stop mode, the CPU does not execute the application program logic.
You can configure whether or not the I/O will scanned during Stop mode.
Communications with the programmer and intelligent option modules continue in Stop
mode. In addition, faulted board polling and board reconfiguration execution continue in
Stop mode.
SVCREQ 13 can be used in the application program to stop the PLC at the end of the next
sweep. All I/O will go to their configured default states, and a diagnostic message will be
placed in the PLC Fault Table.
VersaMax PLC User Manual