Understanding Sensor Terminology; Normally Open, Normally Closed; Ready Signal - Honeywell SmartPAC 2 User Manual

1126800 SmartPAC 2 with WPC Integration

Understanding Sensor Terminology

In order to make the proper settings for your sensors using the SmartPAC 2 display, it is
beneficial to know what certain terms mean. You will see words on the display, such as ready
on, ready off, N/C (normally closed), N/O (normally open), green, green quick check, green
constant, yellow, and red. If you are familiar with die protection sensors and controllers, you
will know what most of these terms mean already. If you do not, these key words are
explained below

Normally Open, Normally Closed

These terms refers to the way a sensor operates.
A normally open (N/O) sensor actuates (signals SmartPAC 2) when the sensor circuit to
SmartPAC 2 switches from open to closed-to-ground. Normally open sensors are broadly
classified as yellow or green sensors.
A normally closed (N/C) sensor works just the opposite of normally open. The sensor circuit
to SmartPAC 2 is closed to ground in its normal state. The sensor actuates when the circuit
opens. Normally closed sensors are classified as red sensors. Most contact type sensors can
be used as either normally open or normally closed depending on how they are connected.
Most sensors are used as normally open just because you do not have any current flowing in
the normal state. Some electronic sensors can be switched to work either as normally open
or normally closed.

Ready signal

The ready signal is the portion of the stroke where a sensor must actuate. For many of your
sensors, like those that monitor part ejection, blow-off, or feed advance, you need to be sure
that the event occurs during a specific portion of each stroke. If the event occurs late, or not
at all, you are likely to have tooling damage. The ready signal tells SmartPAC 2 when to
expect the actuation from the sensor. A ready signal is set only for sensors classified as cyclic
(green) sensors. These are sensors which monitor events that must occur on every stroke.
The term "ready signal" comes from older die protection systems where you had to set a
mechanical cam switch on the press to send a signal to the die protection unit during the
portion of the stroke where the sensor had to actuate. SmartPAC 2 eliminates all this extra
work because it automatically knows the position of the ram at every point in the stroke. But
we still use the term "ready signal" because it is widely understood.
To set a ready signal on SmartPAC 2, you just key in the degrees of the stroke where the
sensor must actuate. The beginning point is called ready on. The end point is ready off. A
separate ready signal can be set for each green sensor. If the sensor does not actuate (closure
to ground) during the ready signal, SmartPAC 2 will send a stop command to the press. The
type of stop can be a top stop, emergency stop, or Smart Stop (see "Considerations for
setting sensor stop type" in this chapter).
Page 12 Chapter 1 Introduction to SmartPAC 2