Mitsubishi Electric MELSEC-Q/L

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7 APPLICATION INSTRUCTIONS

7.6 Structure Creation Instructions

483

• When function devices (FX, FY, FD) are used by a subroutine program, specify a device with (S1) to (S5) corresponding to

the function device. The contents to the devices specified by (S1) to (S5) are as indicated below.

*2 An error will not occur even when the device number specified by (S1) to (S5) is not a multiple of 16 at the digit designation of the bit

device.

[Main routine program]

• (S1) to (S5) can be used by the XCALL instruction.

• The number of function devices used by a subroutine program must be identical to the number of arguments in the XCALL

instruction. Also, the function device and the type of XCALL argument should be identical.

• The device numbers specified as the arguments of the XCALL instruction should not overlap. If they do overlap, it will not

be possible to obtain accurate calculations.

• Up to 16 nesting levels can be used with the XCALL instruction. However, this 16 levels is the total number of levels in the

CALL(P), FCALL(P), ECALL(P), EFCALL(P), and XCALL instructions.

• Prior to execution of the subroutine program, bit data is transmitted to FX, and word data is transmitted to FD.

• After the execution of the subroutine program, the contents of FY and FD are transmitted to the corresponding devices.

• The function devices FX and FY are processed in units of bits. The function device FD is processed in units of 4 words. The size of the data to be dealt with

will differ depending on the device specified in the argument. The device specified as a function device should be secured for the data size. An error will occur

if it cannot be secured for the data size.

Function devices Device Data size Remark

•FX

•FY

Bit device 1 point 

When bit designation is made for

word device

1 bit

• FD When digit designation of a bit device

is used

4 words The data size varies depending on

the instruction to be used.