Lenze DDS v2.0 - Manual (Page 19)

Introduction to IEC 61131-3 programming
Programming languages
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DDS-IEC61131 EN 2.0
Contacts
If a Boolean variable of a contact has the value TRUE, the status ” ON” is transmitted via the
connection line from left to right. Otherwise, the right connection is set to ” OFF” .
•
Contacts can be switched in parallel. For this, one of the parallel branches must transmit the
value ” ON” .
•
Contacts can also be switched in series. For this, all contacts must transmit the status ” ON” .
•
Contacts can also be negated (indicated by a slash in the contact symbol). The contact
transmits the input status if its status is ” OFF” (FALSE) ist.
Coils
In LD, an unlimited number of coils is available on the right side of a network (indicated by brackets).
•
A coil transmits the connection value from left to right and copies the value to the
corresponding Boolean variable.
•
The start line can be set to ” ON” or ” OFF” (depending on the Boolean values TRUE or FALSE).
•
Coils can only be connected in parallel.
•
Coils can also be negated (indicated by a slash in the contact symbol). They then copy the
negated value to the corresponding Boolean variable.
Set/ reset coils
Coils can also be defined as set or reset coils.
A set coil (indicated by the letter ” S” in the coil symbol)can have the status ” ON” , but cannot be reset
to ” OFF” .
•
If the Boolean variable of the set coil has been set to TRUE, it cannot be reset to FALSE.
A reset coil (indicated by an ” R” in the coil symbol) can have the status ” OFF” , but cannot be reset
to ” ON” .
•
If the Boolean variable of the reset coil has been set to FALSE, it cannot be reset to TRUE.
Function blocks in LD
In addition to contacts and coils, it is also possible to enter function blocks and programs in LD.
Function blocks and programs must have an input and output with Boolean values in the network.
They can be used at the same locations as the contacts, i.e. on the left side of the LD network.
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