System Device; Special Relay (Sm); Special Register (Sd); Cpu Buffer Memory Access Device - Mitsubishi Electric MELSEC iQ-R16MTCPU Programming Manual

3.3

System Device

System devices are devices for the system. Allocation and capacity are fixed, and cannot be changed arbitrarily.

Special relay (SM)

These are internal relays whose specifications inside the Motion CPU are fixed, and as with standard internal relays, they
cannot be used at the program. However, they can be turned ON and OFF to control the Motion CPU if required.
Refer to special relays for details on special relays. (Page 426 Special Relays)

Special register (SD)

These are internal registers whose specifications inside the Motion CPU are fixed, and as with standard internal registers,
they cannot be used at the program. However, data can be written to control the Motion CPU if required.
Refer to special registers for details on special registers. (Page 431 Special Registers)
3.4

CPU Buffer Memory Access Device

These devices access memory used to read and write data between CPU modules in a Multiple CPU system.
Specification method
Specify with U [CPU module installation position]\[Communication area][First address in buffer memory].
U 3E \
First address in buffer memory
Communication area
• G: CPU buffer memory
• HG: Fixed scan communication area
CPU module installation position
CPU No.1: 3E0
CPU No.2: 3E1
CPU No.3: 3E2
CPU No.4: 3E3
Ex.
CPU No.2, CPU buffer memory address 4095
 U3E1\G4095
CPU No.3, CPU buffer memory (fixed scan communication area) address 1024
 U3E2\HG1024
3 DEVICES
80
3.3 System Device