Element: Contact

A contact passes on the signal TRUE (ON) or FALSE (OFF) from left to right until the signal reaches a coil in the right side of the network. To this end, the contact is assigned a Boolean variable that contains the signal. To do this, replace the ??? placeholder above the contact with the name of a Boolean variable.

You can arrange several contacts in series or in parallel. If two parallel contacts are used, only one of them has to have the value TRUE for ON to be passed to the right. If contacts are connected in series, all contacts must be set to TRUE for ON to be passed to the right from the last contact of the series. You can therefore use LD to program electrical parallel and series circuits.

A negated contact passes the TRUE signal when the variable value is FALSE. You can use the Ladder → Negate command to enable or disable negation of an inserted contact.