System Device; Function Device (Fx/Fy/Fd) - Mitsubishi Electric MELSEC iQ-R-R00CPU User Manual

21.4

System Device

The system device is used by the system. Assignment/capacity is fixed and cannot optionally be altered.

Function device (FX/FY/FD)

This device is used for the subroutine programs with argument passing. Data is written/read between the subroutine call
sources with argument passing and the subroutine programs with argument passing. When using the function device in a
subroutine program, the device used in each subroutine program call source can be determined. As a result, when using the
same subroutine program, it can be used without being aware of the call source of other subroutine programs.
Function input (FX)
This device is used when passing on/off data to a subroutine program. In the subroutine program, bit data specified in a
subroutine call instruction with argument passing are captured and used for operation. All the bit data specification devices of
the CPU module are available.
Function output (FY)
This device is used when passing operation results (on/off data) in a subroutine program to a subroutine program call source.
Operation results are stored into the device specified in the subroutine program with argument passing. The bit data
specification device other than the CPU module input (X) are available.
Function register (FD)
This device is used for writing/reading between the subroutine call source and the subroutine program. The input/output
condition of the function register is automatically identified by the CPU module. "Source data" in a subroutine program means
data inputted into the subroutine program. "Destination data" in a subroutine program means data outputted from the
subroutine program. One point of a function register occupies maximum of four words and can store 16-bit data, 32-bit data,
64-bit data, single-precision real number, and double-precision real number. However the number of words to be used
depends on the instruction in the subroutine program.
For example, for the destination of addition instruction (+instruction) of 16-bit signed integer, one word is used.
(1)
(1) The data is stored in one point of D0.
Besides, for the destination of addition instruction (ED+instruction) of double-precision real number, four words are used.
(1)
(1) The data is stored in four points of D0 to D3.
21 DEVICES
348
21.4 System Device
CALL P0 D0
D0
D1
D2
D3
D4
CALL P0 D0
D0
D1
D2
D3
D4
P0 + ZR0 K10 FD0
ED+ ZR0 E1.0-3 FD0
P0