Specifications

General programming notes
8.3.1
Address symbols
8
-4
8.3 Address structure
8.3.1 Address symbols
Each STEP7 bit is represented by an address starting with a symbol that identifies the func-
tion of the bit (e.g., input or output). The symbol of the address of an output bit is letter Q,
not letter O (to distinguish from number 0).
In this manual, all bit addresses are expressed in accordance with the IEC international stan-
dard representation. Thus the function of each bit can be easily identified by looking at its
symbol (for example, "I" means an input bit, and "Q" means an output bit).
8.3.2 Bit address
A bit address is expressed in the following format:
Symbol Function Examples
I Input I5.2
Q Output Q54.3
M Memory (internal relay) M12.7
D Data DBX1.1
T
Timer T24
C
Counter C15
P Peripheral
(e.g., analog, direct I/O access)
PIW128
PQW128
Local stack L1.2, LW2
Byte address
Bit address
Address symbol
I 0.0
I 0.1
I 0.2
I 0.3
I 0.4
I 0.5
I 0.6
I 0.7
I 1.0
I 1.1
I 1.2
I 1.3
I 1.4
I 1.5
I 1.6
I 1.7
I 2.0
:
Q 0.0
Q 0.1
Q 0.2
Q 0.3
Q 0.4
Q 0.5
Q 0.6
Q 0.7
Q 1.0
Q 1.1
Q 1.2
Q 1.3
Q 1.4
Q 1.5
Q 1.6
Q 1.7
Q 2.0
:
M 0.0
M 0.1
M 0.2
M 0.3
M 0.4
M 0.5
M 0.6
M 0.7
M 1.0
M 1.1
M 1.2
M 1.3
M 1.4
M 1.5
M 1.6
M 1.7
M 2.0
:
T 0
T 1
T 2
T 3
T 4
T 5
T 6
T 7
T 8
T 9
T 10
T 11
T 12
T 13
T 14
T 15
T 16
:
C 0
C 1
C 2
C 3
C 4
C 5
C 6
C 7
C 8
C 9
C 10
C 11
C 12
C 13
C 14
C 15
C 16
:
DBX 0.0
DBX 0.1
DBX 0.2
DBX 0.3
DBX 0.4
DBX 0.5
DBX 0.6
DBX 0.7
DBX 1.0
DBX 1.1
DBX 1.2
DBX 1.3
DBX 1.4
DBX 1.5
DBX 1.6
DBX 1.7
DBX 2.0
:
入力､出力､ビットメモリ､データの表記
Address for input, output, memory, and data bits
T 1
Address symbol
Number
Address for timers and counters
(0,1,2,3,4,5,6,7,8,9,10,11)
(0,1,2,3,4,5,6,7,)
(I,Q,N,DBX)
(0,1,2,3,4,5,6,7,8,9,10,11)
(T,C)
I 1.2