4.1 User Program Types and Execution Timing
4.1.5 Registers
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Creating User Programs
4.1.5
Registers
Registers are areas that store data within the Machine Controller. Variables are registers with
labels (variable names).
There are two kinds of registers: global registers that are shared between all programs, and
local registered that are used only by a specific program.
Global Registers
Global registers are shared by ladder programs, user functions, motion programs, and
sequence programs. Memory space for global registers is reserved by the system for each reg-
ister type.
Ladder
programs
Global registers
S registers
65,535 words
M registers
1,048,576 words
G registers
2,097,152 words
I registers
65,536 words
Input data +
Monitor
para
CPU interface
inputs
O registers
65,536 words
Output data +
Setting
para
CPU interface
outputs
C registers
16,384 words
User functions
Motion
programs/
sequence
programs