15
The Function of Secret Register
A part of the FlashROM register is used to store data in soft components, which are
represented by the symbol FS. The values in the FS register can be written but can not be
read, so they can be used to protect the intellectual property rights of users.
Address Allocation Principle
In the basic unit, FS registers are addressed in decimal numbers.
Since the number of FS registers of different types of PLC may be different, please refer to
the "PLC Initial Settings" shown in the online PLC software, generally FS0-FS47.
Attention Points in Use
The storage area can remember data even if the battery is powered down, so it can be used to
store important process parameters. FS can be written about 1,000,000 times, and it takes
more time to write each time. Frequent writing will cause permanent damage to FS, so it is
not recommended that users write frequently. When using MOV instruction to transmit data
to FS, the rising edge is valid.
The value of the soft element can be set arbitrarily in the FS register, but the value of the
register can not be read (always returned to 0); and it can not be compared with the register
in the PLC software, only with the constant, so the actual value of the register can not be
read.
B means Binary, K represents Decimal, H represents Hexadecimal. They are used to set
timers and counters value, or operands of application instructions. For example hex FF will
be HFF.
2-2
.
Structure of Soft Components
2-2-1
.
Structure of Memory
In XD/XL series PLC, there are many registers. Besides D, HD, FlashROM registers, we can
also combine bit to register.
For common use, 16 bits
For common use, 32 bits (combine two continuous 16-bits registers)
For power off retentive use, cannot modify the retentive range
For special use, occupied by the system, can’t be used to common instruction parameters
For offset use (indirect assignment)
Constant (B) (K) (H)
Data Register D, HD
Special secret Register (FS)