PLC concepts
4.2 Accessing data
S7-200 SMART
76
System Manual, V2.3, 07/2017, A5E03822230-AF
V (variable memory)
You can use V memory to store intermediate results of operations being performed by the
control logic in your program. You can also use V memory to store other data pertaining to
your process or task. You can access the V memory area in bits, bytes, words, or double
words:
Table 4- 6
Absolute addressing for V memory
Bit:
V
[byte address].[bit address]
V10.2
Byte, Word, or Double Word:
V
[size][starting byte address]
VB16,
VW100,
VD2136
M (flag memory)
You can use the flag memory area (M memory) as internal control relays to store the
intermediate status of an operation or other control information. You can access the flag
memory area in bits, bytes, words, or double words:
Table 4- 7
Absolute addressing for M memory
Bit:
M
[byte address].[bit address]
M26.7
Byte, Word, or Double Word:
M
[size][starting byte address]
MB0, MW11,
MD20
T (timer memory)
The CPU provides timers that count increments of time in resolutions (time-base increments)
of 1 ms, 10 ms, or 100 ms. Two variables are associated with a timer:
●
Current value: this 16-bit signed integer stores the amount of time counted by the timer.
●
Timer bit: this bit is set or cleared as a result of comparing the current and the preset
value. The preset value is entered as part of the timer instruction.
