PID Loop - Application Example and Hardware Explained. Part 3 of 11, Productivity3000


Uploaded by automationdirect on 16.01.2012

Transcript:
I will next explain the application that we will use as our example and cover the hardware
that was put together to make it work.
We start with a cylindrical polyethylene tank that can hold up to ten gallons of water or
other fluid. We already determined we need the ability to maintain a known volume within
the tank that our process will rely on to accurately mix additive as the mixture is
being used at a random rate. The volume in the tank will be handled with a small Diaphragm
Pump controlled by a variable DC motor controller that can accept a 0 to 10 volt DC analog signal
from our Productivity 3000. We will monitor the level in the tank by means of an Ultrasonic
Sensor that will produce a 0 to 10 volt DC analog output signal that is proportional
to the distance between the sensor and the surface of the water. The sensors output will
be connected to a Productivity 3000 Analog Input Module.
Here we see a diagram representing the working application. The Process and Reservoir Tanks
are shown with the interconnecting tubing for both filling and draining the Process
Tank. The Ultrasonic Sensor used to measure water level is shown mounted through the lid
of the Process Tank. We will use the level to calculate the volume of water contained
in the tank. In our demonstration, a manually operated ball valve will be used to set the
rate at which the mixture is used through a siphoning action, with the water returned
to a Reservoir Tank, so it can be reused. A hand operated Primer Bulb, as might be used
on a gas tank for an outboard engine on a boat, is used to initially start the drainage
flow, with a siphon tube used to prevent loss of flow once the system is primed.
Much of the design that went into our example application was based on using products that
are carried by AutomationDirect. Of course the Productivity 3000 Programmable Automation
Controller is our main focus and feature for this tutorial. With its abilities, and the
ease of adding a C-more Touch Panel, we are able to quickly setup, control and monitor
our application. And it was a no brainer to use ADCs sensors, relays, push buttons, power
supplies, protective devices and wiring components to round out the design.
Here we see the components from other sources that were used to complete our application
design. These included the polyethylene tanks, Diaphragm Pump, DC motor controller, float
switch, the Primer Bulb, vinyl tubing, fittings, and a 19 inch relay rack.
The arrangement of the equipment used for the example application was designed so all
of the components would fit on a portable relay rack.
On the front includes the Productivity 3000, C-more Touch Panel, Power On and Emergency
Stop push buttons, Process Tank with Ultrasonic Level Sensor and overflow float switch, and
a Stack Light Tower mounted off to the side. On the rear are found the ZipLink modules,
power supplies, Stride Ethernet switches, relays, circuit protection, DC motor controller,
reservoir tank, and Diaphragm Pump with a 12 volt DC motor. Also included are terminal
blocks and wire duct to keep the wiring neat. ZipLink modules and cables aided in allowing
the wiring to take minimum time. Seen next is a series of wiring diagrams,
or if you prefer, schematics, that detail the wiring in our application example. In
particular is the use of protective devices and separate DC power supplies for the general
DC devices, analog input and output signals, and DC power to the Diaphragm Pump motor.
The first diagram includes the Power On, Emergency Stop, relays, float switch and general 24
volt DC circuitry. Sheet 2 of the diagrams shows power and communications to the Productivity
3000 and C-more Touch Panel.
Also shown is the 24 volt DC power for the Stride Ethernet switches and the analog signals.
Sheet 3 continues with the Productivity 3000 discrete DC input and output I/O modules,
and the use of ZipLink modules and cables to make the actual wiring clean and simple
to accomplish.
The last diagram includes our Productivity 3000 analog input and output modules, ZipLink
modules and cables to keep the analog signal wiring simple, connections to the Ultrasonic
Sensor, and a Rhino 12 volt DC power supply for the Dart DC motor speed controller used
to power the Diaphragm Pump motor.
The Ultrasonic Sensors 0 to 10 volts DC signal is wired into the first channel of the analog
input module by way of a ZipLink module and interconnecting cable.
The first channel of the analog output module, using a ZipLink module and interconnecting
cable, provides the 0 to 10 volts DC signal to the Dart DC motor speed controller, which
allows the Diaphragm Pump to produce a 0 to 1 gallon per minute flow rate to the Process
Tank.
Next we need to configure the jumpers on the analog input module so the 0 to 10 VDC signal
from the Ultrasonic Sensor can be used to determine the water level in the Process Tank.
The P3-04ADS Analog Input Module we have chosen has the ability to be configured to accept
either voltage or current signals, and each type of signal can also be configured for
different ranges, such as 0 to 5 volts DC, 0 to 10 volts DC, 4 to 20 milliamps, etc.
To keep it simple, we will set the Analog Input Module up so all four channels will
accept a 0 to 10 volts DC signal. This will provide a 0 to 65,535 count range within our
Productivity 3000 ladder logic program.
Join me in Part 4 of this video series as I cover configuring our hardware, explain
the use of Tagnames, and do some calculations to get our signals into understandable and
useful engineering units.