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A programmed supervision is indicated by the letter V to the left of the step at all
display levels.
You program supervisions at the single step display level. A maximum of
32 Ladder Logic/FBD elements can be programmed per supervision. The result is
managed automatically by the system.
If the logic operation of the conditions is satisfied, there is a disturbance and the
event V1 is signaled. The sequencer does not switch to the next step. The current
step, however, remains active. The step activation time Si.U is stopped as soon as
the condition is satisfied.
If the logic operation of the conditions is not satisfied, there is no disturbance. If the
transition following is satisfied, the sequencer switches to the next step.
Permanent instructions
You program permanent instructions with the familiar Ladder Logic/FBD elements.
For more information about entering Ladder Logic/FBD networks in a field for
permanent instructions, refer to Section "Permanent Instructions".
7.6
Ladder Logic Elements for Programming Conditions
Ladder Logic Elements
A Ladder Logic program follows the power flow between power rails. The individual
Ladder Logic elements carry binary information: Signal state "0" (current not
flowing) or "1" (current flowing).
Ladder Logic Element
Normally open contact
<Address>
Normally closed contact
<Address>
S7-GRAPH for S7-300/400 Programming Sequential Control Systems
C79000-G7076-C526-01
Address
Data type
<address> BOOL,
TIMER,
COUNTER
<address> BOOL,
TIMER,
COUNTER
Programming Actions and Conditions
Memory
Description
Area
I, Q, M, T, C
The normally open contact has
data bit
signal state "1", when the signal
state of the address is "1".
The address specifies the bit whose
signal state is queried.
I, Q, M, T, C
The normally closed contact has
data bit
signal state "1", when the signal
state of the address "0".
The address specifies the bit whose
signal state is queried.
7-17
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