Lessons · Industrial control · normally open contact
Normally open: passes power when TRUE
[Name] passes power only while its input is true. Contacts in series are AND.
Hone is a place to practise programming. This is one of its lessons, written out in full and free to read without an account.
What it is for
Pushbuttons, sensors, permissives: 'this must be on'.
How to think about it
Must this be on? For every condition that must be true, one normally open contact, in series.
Worked example
[Start] [Guard] (Motor)Both true, motor runs.
Your turn
Both A and B.
[A] (Out)
Run a rung and watch the scan
The trap
Reading [Name] as 'the button' rather than 'the button is pressed'. A contact is a condition, not a device.
Practise normally open contact on HoneA question on it now, a coding challenge where there is one, and it is remembered for review. Free, no email needed.