Siemens SIMATIC S7-1200, Системное руководство

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97BPLC concepts
4.2 Data storage, memory areas, I/O and addressing
S7-1200 Programmable controller
System Manual, 11/2011, A5E02486680-05
81
Each different memory location has a unique address. Your user program uses these
addresses to access the information in the memory location. References to the input (I) or
output (Q) memory areas, such as I0.3 or Q1.7, access the process image. To immediately
access the physical input or output, append the reference with ":P" (such as I0.3:P, Q1.7:P,
or "Stop:P").
Table 4- 8 Memory areas
Memory area Description Force Retentive
Copied from physical inputs at the beginning of the scan
cycle
No No I
Process image input
I_:P
1
(Physical input)
Immediate read of the physical input points on the CPU,
SB, and SM
Yes No
Copied to physical outputs at the beginning of the scan
cycle
No No Q
Process image output
Q_:P
1
(Physical output)
Immediate write to the physical output points on the
CPU, SB, and SM
Yes No
M
Bit memory
Control and data memory No Yes
(optional)
L
Temp memory
Temporary data for a block local to that block No No
DB
Data block
Data memory and also parameter memory for FBs No Yes
(optional)
1
To immediately access (read or write) the physical inputs and physical outputs, append a ":P" to the address or tag
(such as I0.3:P, Q1.7:P, or "Stop:P").
Each different memory location has a unique address. Your user program uses these
addresses to access the information in the memory location. The absolute address consists
of the following elements:
●
Memory area identifier (such as I, Q, or M)
● Size of the data to be accessed ("B' for Byte, "W" for Word, or "D" for DWord)
● Starting address of the data (such as byte 3 or word 3)
When accessing a bit in the address for a Boolean value, you do not enter a mnemonic for
the size. You enter only the memory area, the byte location, and the bit location for the data
(such as I0.0, Q0.1, or M3.4).