Detecting objects with a Productivity 2000
is easy. In this video we’ll use – and 3 proximity sensors, an Ultrasonic sensor and 3 different
types of Photo sensors diffuse, retro-reflective and through beam to detect the presence of
an object. Here’s what it looks like on the test rack.
Here are the three Inductive Proximity Sensors, the Ultrasonic sensor and the Through Beam,
diffuse and retro reflective photo-optic sensors. First we’ll connect the proximity and ultrasonic
sensors, then we’ll swap those out with the photo sensors. The Productivity 2000 has a
4 slot base with AC Power Supply, the CPU and an 8 input module and an 8 output module
which we aren’t using in this demo. Two of the proximity sensors are intentionally
NPN and the last proximity sensor and the ultrasonic are PNP just so you can see how
to connect the different sensor types to your controller.
Since we have both types of sensors, we need to make sure the PLC input module can handle
both NPN and PNP. This Productivity 2000 input module has two commons. That’s perfect because
we can simply connect one common to the positive voltage rail so the NPN sensors can pull the
I/O terminal low when they activate, and we’ll connect the other common to the negative rail
so the PNP sensor can pull the I/O pin up when it goes active.
And that’s all you really need to remember when you have an NPN sensor which sinks current,
you need an input module that can source the current. When you have a PNP sensor that sources
current, you need an Input module that can sink the current. And since this input module
handles both we’re in good shape. AutomationDirect’s sensors have a diagram
on the sensor or on the wire showing exactly how to wire the sensor. This little box is
the sensors load – which is the PLC and for this sensor we see that the PLC provides or
sources current from the positive rail to the input of this sensor. So we know without
even looking at the part number, that this must be an NPN sensor to sink that sourced
current to ground. So we connect the two NPN sensors to this
block of I/O with the positive common and we connect the two PNP sensors to this block
with a grounded common. Perfect. If we bring up the Productivity Suite software
and connect to the PLC, we can instantly see the results in the dataview when I pass metal
in front of the inductive proximity sensors, we see the result and when I wave my hand
in front of the Ultrasonic we also see the result too. Easy.
And check this out. This I/O view lets me view and manipulate every I/O in the entire
controller system at a glance. I can even enable forcing of the individual I/O or the
entire module simply by right clicking. I love that because now I can view and modify
any I/O independent of my ladder code that really helps when I’m trying to figure out
if the issue is in my code or the hardware. And while we are here, did you know you can
right click on the Dataview column header to enable and disable columns? That really
helps when you are tight on screen real estate. Notice that even though the NPN sensors are
pulling the input terminal low, and the PNP’s are pulling it high, none of that matters
here. All we see in the dataview is if the sensor is ACTIVE. Once the sensor is properly
wired you don’t need to worry about whether the signal is high or low.
To use that in your ladder code you just bring the inputs in as you would any other contact.
The NPN inputs are located at input 1 and 2 and the PNP inputs are located at inputs
5 and 6. The photo-optic sensors are exactly the same
thing. We have a through beam, a diffuse and a retro reflective sensor, but all we really
care about is: are they NPN or PNP? The through beam is NPN and the other two are PNP, so
we connect the NPN sensor to the I/O block with the Positive common and the PNP sensors
to the I/O block with the negative or grounded common.
I swapped out the wiring of the proximity sensors with the photo sensors so when we
monitor the ladder code we get the exact same result.
Mechanical switches can be connected as either sinking or sourcing. AC Proximity sensors
can also be used for sinking or sourcing, just make sure you have an input card that
can handle the AC voltage. If you have any questions, please don’t hesitate
to contact AutomationDirect’s Free Award Winning Tech Support during regular business hours.
They will be happy to help. Also, don’t forget the forums. There are lots of folks there
that love to share their years of experience. Just don’t post any Tech Support Questions
there AutomationDirect’s support staff doesn’t monitor the forums on a regular basis.