Download MELSEC-L CPU Module User`s Manual (Function Explanation

5.2.13
Link register (W)
The link register data register whose device number is represented in hexadecimal. In the link register, numeric
data (-32768 to 32767, or 0000H to FFFFH) are stored.
(1) Bit structure of the file register
(a) Bit structure and write/read unit
One point of the link register consists of 16 bits, and data can be written or read in units of 16 bits.
to
b15
b0
Wn
The most significant bit is a sign bit.
Link register data are handled as signed data. In the case of the hexadecimal notation, 0000H to FFFFH can be stored.
However, because the most significant bit represents a sign bit, decimal values that can be specified are -32768 to 32767.
(b) Using in a 32-bit instruction
For a 32-bit instruction, two consecutive points of the data register (Wn and Wn+1)are the target of the
processing. The lower 16 bits correspond to the link register number (Wn) specified in the program, and the
higher 16 bits correspond to the specified link register number + 1.
Ex. When W12 is specified in the DMOV instruction, W12 represents the lower 16 bits and D13 represents the
higher 16 bits.
Processing target: W12, W13
W13
W12
Upper 16 bits Lower 16 bits
Data of -2147483648 to 2147483647 or 00000000H to FFFFFFFFH can be stored in a two-point area of the link
register. (The most significant bit in a 32-bit structure is a sign bit.)
(2) Retention of stored data
The data stored in the link register are held until other different data are stored. Note that the stored data are
initialized when the CPU module is powered off or reset.
When using a link device in the network module by using the points of the link register in the CPU module (default: 8192
points) or greater, change the points setting of the link register in the "Device" of the "PLC Parameter".
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