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Appendix
Appendix
13. Local/Global Variables and Flags
Description
The internal variables and flags used in the SEL language are classified into local and global types.
The data range used commonly by all programs is called the global range, while the data range used only by
each program is called the local range. When multi-tasking programs are run simultaneously, the global range
must be used to synchronize the programs and allow cross-referencing of variables among the programs.
Example of Use
Program handshake
Program A Program B
Use of global flags with the above two programs permits handshake between the programs, and the actuator
moves per “MOVL 1” in program A, moves per “MOVL 2” in program B, and then move per “MOVL 3” in program
A, for example.
Backup in Battery
The XSEL controller has a built-in battery for retaining variables and flags used in the programs. For both
variables and flags, only those in the global range will be retained after the controller power is turned off. The
variables and flags in the local range are cleared when the program is started (the variables are reset to “0,”
while the flags turn OFF).
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