Command: Insert Contact
Symbol: 
, in the editor 
Shortcut: Ctrl + K
Function: The command inserts a contact in the network, to the left of the selected element. When you drag the element from the toolbox to the implementation part, the plus symbol at the cursor (
) helps you recognize the possible insertion positions.
Call: Ladder menu; context menu
Requirements: A line or a contact is selected.
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. For this purpose, a Boolean variable containing the signal is assigned to the contact. To do this, replace the (???) placeholder above the contact with the name of a Boolean variable.
You can arrange multiple contacts both in series and in parallel. In the case of two parallel contacts, only one needs to get the value TRUE in order for ON to be passed on to the right. When contacts are connected in series, all of them have to get the value TRUE in order for ON to be passed on to the right by the last contact in the series. As a result, you can use LD to program electrical parallel and series connections.
A negated contact (
) passes the TRUE signal when the variable value is FALSE. You can use the command to enable or disable negation of an inserted contact.