LINK Systems OmniLink 5000 - Manual (Page 30)

3-9
Figure 3.12
A Track PLS Invert type input is used
to monitor an air cylinder
An example of the use of a Track PLS Invert type on an input is the monitoring of an air cylinder
used for parts ejection, as shown in Figure 14. Suppose a PLS output on the System 5000 is used
to activate the cylinder, with the power source for the cylinder switched through the N.O. contacts
of the PLS relay. A probe type switch is located such that it will close and ground the die protection
input when the air cylinder is retracted (at the home position). Should the air cylinder jam in the
extended position, the switch will not close when the output turns off. The die protection module
will then detect a fault and stop the press before the dies can close on the cylinder.
Notice in this example that when the PLS
output turns on, the air cylinder extends;
this in turn opens the switch, turning off
the die protection input. In this case the
on/off state of the input is inverted from the
PLS output state. In this application and
other similar ones, Track PLS Invert should
be chosen as the input type. As previously
described, for Track PLS Invert inputs the
module will read the state of the input and
then invert that reading internally before
comparing it to the PLS output.