Lenze PLC Designer PLC Designer (R2-x) - Manual (Page 74)

L-force | PLC Designer
What is What in PLC Designer
72 DMS 3.2 EN 02/2011 TD29

Coil
On the right side of a network in LD there can be any number of so-called coils which
are represented by parentheses:( ). They can only be in parallel. A coil transmits the
value of the connections from left to right and copies it in an appropriate Boolean
variable. At the entry line the value ON (corresponds to the Boolean variable TRUE) or
the value OFF (corresponding to FALSE) can be present.
Contacts and coils can also be negated (in the example the contact SWITCH1 and the
coil %QX3.0 is negated). If a coil is negated (recognizable by the slash in the coil
symbol: (/)), then it copies the negated value in the appropriate Boolean variable. If a
contact is negated, then it connects through only if the appropriate Boolean value is
FALSE.
Function blocks in the Ladder Diagram
Along with contacts and coils you can also enter function blocks and programs In the
network they must have an input and an output with Boolean values and can be used
at the same places as contacts, that is on the left side of the LD network
Set/Reset coils
Coils can also be defined as set or reset coils. One can recognize a set coil by the "S" in
the coil symbol: (S)) It never writes over the value TRUE in the appropriate Boolean
variable. That is, if the variable was once set at TRUE, then it remains so.
One can recognize a reset coil by the "R" in the coil symbol: (R)) It never writes over the
value FALSE in the appropriate Boolean variable: If the variable has been once set on
FALSE, then it remains so.
LD as FBD
When working with LD it is very possible that you will want to use the result of the
contact switch for controlling other POUs. On the one hand you can use the coils to
put the result in a global variable which can then be used in another place. You can,
however, also insert the possible call directly into your LD network. For this you
introduce a POU with EN input.
Such POUs are completely normal operands, functions, programs, or function blocks
which have an additional input which is labeled with EN. The EN input is always of the
BOOL type and its meaning is: The POU with EN input is evaluated when EN has the
value TRUE.
An EN POU is wired parallel to the coils, whereby the EN input is connected to the
connecting line between the contacts and the coils. If the ON information is
transmitted through this line, this POU will be evaluated completely normally.