User Manual PLC-3 BACKUP CONC(OR.DU1 Owner's manual

Using the 1775MX
Memory Communication Module
Chapter 4
4-17
Operation of a memory communication module using message (MSG)
instructions follows the same convention as other modules in a PLC-3
system. The memory communication module has additional functions,
however, that let you enable and disable operation of memory
communication modules from the ladder program.
Table 4.G lists the commands available for use in message instructions. All
of the functions available in LIST are also available in message
instructions. In addition, there are four commands - TRANSFER DATA,
TRANSFER $<file list>, DISABLE OUTPUTS, PROGRAM CONTROL
- available in message instructions that are not available when using LIST
control.
Table 4.G
MSG
Instruction Functions
Command Abbreviation Description
STOP STO The memory communication module stops
both continuous data transfers and continuous
file transfers to the backup processor.
START $<file list> STA $<file list> The memory communication module transfers
the selected files from the primary to the
backup processor continuously. You can
select up to 16 files for the transfer.
TRANSFER $<file list> T $<file list> The memory communication module transfers
the selected files from the primary to the
backup processor one time only. You can
select up to 16 files for the transfer.
START DATA STA D The memory communication module transfers
the entire data table except the data table
status section from the primary to the backup
processor continuously.
TRANSFER DATA TD The memory communication module transfers
the entire data table except the data table
status section from the primary to the backup
processor one time only.
DOWNLOAD DO The memory communication module stops
any data transfer in progress and transfers the
entire contents of PLC3 memory from the
primary to the backup processor.
LOCK LO The memory communication module acquires
the edit resource for both the primary and
backup processors. This protects the ladder
program in the current context from being
edited with a programming terminal.
UNLOCK U The memory communication module releases
the edit resource for both the primary and
backup processors.
Using Message Instructions
for Control