LINK Systems OmniLink II Press Automation Control - Manual (Page 116)

August 30, 2002 Manual Version 1.0 6.11
Static Normally Off, the input should NOT be On under normal operation. In this case when the input
switches On, a stop will be issued by the Digital Die Protection and Process Monitor. If the input is
programmed as Static Normally On, the input should be On under normal operation. In this case when
the input switches Off, a stop will be issued by the Digital Die Protection and Process Monitor.
An example of the use of a Static Normally Off
input is stock buckling detection, as shown in
Figure 6.5, part A. The stock to be fabricated is
placed between a dual probe in the normal
position. The probe remains Off (ungrounded)
unless the stock buckles upward or downward
far enough to touch the upper or lower portion
of the probe, turning On (grounding) the
normally open input, causing a fault.
An example of the use of a Normally On input is
an end of stock sensor, as shown in Figure 6.6.
A probe is mounted so that it is On (grounded)
by the stock being fed into the production
machine. When the end of stock is reached, the
probe will no longer contact the stock, turning
Off the input and causing a fault.
An additional feature of Static type inputs is the
delay timer which is programmed by the
operator. A programmed time of zero forces
ordinary operation of the static input as
described above, i.e., if the input is not in the
'normal' state, a fault will occur immediately.
However, if a value other than zero is
programmed the input is allowed to change from
the normal state for the length of time
programmed without a fault occurring. If the
input does not return to the normal state before
the time expires, a fault is generated. This
allows the operator to avoid nuisance faults from
sensors that 'bounce' open or closed
momentarily. The delay time can range from 0
to 65535 milliseconds (65.535 seconds) in 1
millisecond increments.
Figure 6.5 Static Normally Off Inputs
Figure 6.6 Static Normally On Inputs