Rockwell Automation 1775-MX_S4A,D17756.3.1 User Manual PLC-3 BACKUP CONC(OR.DU1 - Manual (Page 78)

Using the 1775ĆMX
Memory Communication Module
Chapter 4
4-31
List Control Command
The LIST CONTROL command lets you redirect control of a memory
communication module from the ladder program to LIST. Only the
primary processor can execute the LIST CONTROL command.
After the primary processor executes a message instruction containing the
LIST CONTROL command, operation of the memory communication
module will be controlled by selections in LIST. Any subsequent message
instructions containing commands intended for a memory communication
module will be ignored.
Program Control Command
The PROGRAM CONTROL command lets you redirect control of the
memory communication module from LIST to message instructions in the
ladder program of the primary processor. Only the primary processor can
execute a PROGRAM CONTROL command.
After the primary processor executes a message instruction containing the
PROGRAM CONTROL command, operation of the memory
communication module will be controlled by subsequent message
instructions in the ladder program. As long as the memory communication
module is being controlled by the ladder program, selections made in LIST
will not affect the operation of the memory communication module until:
either the ladder program executes a message instruction containing a
LIST CONTROL command, or
the primary processor is placed in program load mode.
Transfer Control Command
The TRANSFER CONTROL command lets you force a switchover from
the primary processor to the backup processor.
After the primary processor executes a message instruction containing the
TRANSFER CONTROL command, the following events occur:
switchover begins
the primary processor shuts down
the backup processor takes control of outputs.