supporting Sequence of Events

Publication 1732E-UM002A-EN-P - March 2010
Glossary 105
normally closed
Contacts on a relay or switch that are closed when the relay is de-energized or
the switch is deactivated; they are open when the relay is energized or the
switch is activated. In ladder programming, a symbol that allows logic
continuity (flow) if the referenced input is logic “0” when evaluated.
normally open
Contacts on a relay or switch that are open when the relay is de-energized or
the switch is deactivated. (They are closed when the relay is energized or the
switch is activated.) In ladder programming, a symbol that allows logic
continuity (flow) if the referenced input is logic “1” when evaluated.
off-delay time
The OFF delay time is a measure of the time required for the controller logic
to recognize that a signal has been removed from the input terminal of the
controller. The time is determined by circuit component delays and by any
filter adjustment applied.
offline
Describes devices not under direct communication.
offset
The steady-state deviation of a controlled variable from a fixed point.
off-state leakage current
When an ideal mechanical switch is opened (off-state) no current flows
through the switch. Practical semiconductor switches, and the transient
suppression components which are sometimes used to protect switches, allow
a small current to flow when the switch is in the off state. This current is
referred to as the off-state leakage current. To ensure reliable operation, the
off-state leakage current rating of a switch should be less than the minimum
operating current rating of the load that is connected to the switch.
on-delay time
The ON delay time is a measure of the time required for the controller logic to
recognize that a signal has been presented at the input terminal of the
controller.
one-shot
A programming technique that sets a bit for only one program scan.