Pneumatics and Hydraulic control / Mechatronic system
Dr.Krit Jiamjiroch
PROGRAMMABLE LOGIC
CONTROLLER.
A Programmable Logic Controller, PLC or is a kind of single board controller used for automation
of electromechanical processes, such as control of machinery on car assembly lines, canning and food
process. Unlike general-purpose computers, the PLC is designed for multiple inputs and output
arrangements, add in temperature module etc. Programs to control machine operation are typically
stored in a non-volatile memory. A PLC is an example of a hard real-time system since output results
must be produced in response to input conditions within a limited time, otherwise unintended operation
will result.
OMRON CP1L - High Performing Programmable Controller with Embedded Ethernet
1. Hardware
There are some factors that you may consider before that you are going to install PLC into your
systems; for example: number of Input/output, memory and interfacial ports or communication. For
example, Figure A shows a HDMI of a Recycling carbon fibre process. For this rig, we have to list the
number of temperature measurements points and other inputs. After the list is provided, it was end-up
with 10 points of temperature measurement position, 10 points of the analogue inputs, 10 points of
digital input and 8 points of digital output.
Pneumatics and Hydraulic control / Mechatronic system
Dr.Krit Jiamjiroch
Figure A Recycling process by a Fluidised bed
2. Software
There are nowadays a lot manufacturers provided the PLC on a Market, for example OMRON,
Mitsubishi, Semen and Allen-Bradley. These maker are provided their own software; hence, software or
interfacial language is one of the most factors before buy a controller. In the fact that these software are
trended to accept the same general language but they may have many different details, give you an
headache. Thus, a number of engineers often goes for their familiar PLC brands if they have choices.
3. OMRON PLC
OMRON is one of the Japanese electronic compartment company. There are many products
under this brand like relay, switch and sensors and PLC. At the Thammasat University, we teach several
Brand like a Semen, Brake and OMRON; however, OMRON is accepted as a good one for start as it can
obtainable on Thai market and inexpensive model. The specification of this PLC is shown in Table A and B
Pneumatics and Hydraulic control / Mechatronic system
Dr.Krit Jiamjiroch
Specification for OMRON PLC
Pneumatics and Hydraulic control / Mechatronic system
Dr.Krit Jiamjiroch
4. Ladder Diagram
One of the famous interface language for PLC is a ladder diagram, similarity like a relay and
switch in a circuit. This language is a symbolic language; thus, you just only drag and drop the
components into a working area. For Ladder diagram, it seems like a ladder that composed at least one
rung. Rung is just a memory line that would contain many contacts and output coil or other kind of
instructions.
Contact
Coil
Instructions
The classical example for the ladder may be single line with one contact and one coil as show in
figure below.
10000
00000
Before
After
Pneumatics and Hydraulic control / Mechatronic system
Dr.Krit Jiamjiroch
It seems that the concept of this ladder diagram may similar as an electrical diagram.
10000 = 00000 or not 000001
Interlocking
W000 = (00000 or w0000) and not 000002
Pneumatics and Hydraulic control / Mechatronic system
Dr.Krit Jiamjiroch
http://www.lpc.rmutl.ac.th/elcen/elearning/motorcontrol/module8/motor.html
Pneumatics and Hydraulic control / Mechatronic system
Dr.Krit Jiamjiroch
Pneumatics and Hydraulic control / Mechatronic system
Dr.Krit Jiamjiroch
First, we have to initiate a PLC. It can see that CP1L is a CPU and its
connection is USB port as shown in Figure A.
Figure A
Pneumatics and Hydraulic control / Mechatronic system
Dr.Krit Jiamjiroch
Figure B
Pneumatics and Hydraulic control / Mechatronic system
Dr.Krit Jiamjiroch
Pneumatics and Hydraulic control / Mechatronic system
Dr.Krit Jiamjiroch
AC motor
If you have been looking at the terminal box of the 3 phases motor, the terminal may labels with
U1,V1,W1 and U2,V2,W2. These Ux Yx Wx terminals may reference to the different phases of coil inside
the motor. According to table 1, it shows the identical symbol for the difference phases based on its
geographic area. So, in order to match the generator to the 3 phases motor may follow this table. In this
case, for 3 phase motors there are 6 terminal with 3 phases power supplies so that there are (3P6)
possibilities to matching these motor with its power supplies.
Table 1
Pneumatics and Hydraulic control / Mechatronic system
Dr.Krit Jiamjiroch
Although, it could be start motor as following the connections based on table, the motor will turn in
certain direction. In this case, the motor may go in forward direction (ccw) but what is happen if you
connect these motor the wrong sequences.
STAR-Delta Start
It seems that it could not directly start 3 phases AC motor with more than 5kW capacity because the
motor would be high current consumption. The peak current may roughly 5-7 times of the normal
operating current for the same motor.
circumstances.
Hence, the start-delta technique may apply for this