7.PLC storage area
7.1 Storage area types and properties
Bit
Byte
Word
Double Word Read / write
Retain
Force
Region
Illustration
Read / write
Read / write
Read / write
NO
YES
Discrete input image register
I
and
Read / write
Read / write
Read / write
Read / write
NO
YES
Discrete output and image register Internal memory bit Special memory bit （ SM0 - SM29 Read - only)
Q
Read / write Read / write
Read / write Read / write
Read / write Read / write
Read / write Read / write
YES
YES
M
NO
NO
SM
Read / write Read / write （ T bit ） Read / write （ C bit ）
Read / write
Read / write Read / write （ T Current value ） Read / write （ C current value ）
Read / write
YES
YES
Variable memory
V
NO
NO
T current value YES C current value YES
T bit NO
Timer current value and timer bit
T
NO
NO
C bit NO
Counter current value and counter bit Current value of high speed counter
C
HC
NO
NO
NO
read - only NO
NO
Analog input NO
AI
NO
Read - only
NO
NO
YES
Analog output
AQ
NO
NO
write only
NO
NO
YES
Read / write Read / write
Read / write Read / write
Read / write Read / write
Accumulator register
AC
NO
NO
NO
Read / write
Local variable memory
L
NO
NO
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