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Password Read Protection FLASH Register (FS)
A part of the FlashROM register is used to store data 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.
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 host computer software, only with the constant, so the actual value of the register can not
be read.
This storage area can remember data even if the battery is powered down, so it can be used to
store important process parameters.
Note:
(1) When using MOV instruction to transmit data to FD, SFD and FS, only the rising edge is
valid, even if the driving condition is normally open/closed coil, the instruction is executed
only once.
(2) Flash registers can be written about 1,000,000 times, and each write is erased for the
whole Flash registers, which is time-consuming. Frequent writing will cause permanent
damage to Flash registers, so it is not recommended that users write frequently. Do not use
oscillating coil (e.g. SM11) as driving condition.
(3) When data is transmitted to the same Flash register several times, if the value in the source
register does not change from the previous transmission, the transmission instruction will not
be executed even if the driving condition is established again. For example, if the value in D0
is transmitted to FD100, the value in D0 is 300 when the transmission instruction is executed
for the first time; if the driving condition is established for the second time, the transmission
instruction is not executed if the value in D0 is still 300.
(4) In order to prevent the interference of burr signal when transmitting data to Flash
registers, it is not recommended to use coils such as SM0 and SM2 as direct driving
conditions. It is suggested that the transmission instructions be executed after the PLC power-
on for a period of time.
2-11
.
Constant
XD/XL series PLC has the following 5 number systems.
DEC: DECIMAL NUMBER
The preset number of counter and timer ( constant K)
The number of Auxiliary relay M, HM; timer T, HT; counter C, HC; state S, HS; register D,
HD.
Set as the operand value and action of applied instruction (constant K)
Data process