1. I/tro0u%t$o/ Pneumatic controls are very common in industrial use, primarily for applications that require a fixed distance travel of or reciprocation of objects. Examples include transfer of materials between conveyors, clamping objects for assembly or testing, punch presses etc. Compressed air is used to generate the actuating action, and PLC is commonly used for pneumatic systems. PLC is an electronic device developed specifically to operate on the shopfloor. !t is rugged enough to perform reliably in the plant floor environment. "part from the design advantages the most significant reason for using PLC is the programming language# relay ladder logic. $he close correspondence of ladder logic to relay circuits is the reason for acceptance of PLC%s on the shopfloor by engineers and operators. 2. Obe%t$e $o become familiar with PLC control of pneumatic components used in building sequential circuits for industrial automation. $o design and implement a PLC program for a given cycle of operations involved multiple cylinders. 3. Eper$#e/ta Pro%e0ure &.' !nitial (etup of PLC and pneumatic components Connect the &pin plug of the PLC to the mains. Plug the communication cable from the PC to the )(*++ socet of the PLC. -ith the cables provided, connect the input and output ports of the PLC according to the table and diagram below#
utput Ports /+ /& /* /4 /6 /7 /'2 /''
$argets
!nput Ports
(ource
!nput Ports
(ource
"0 30 C0 50 " 3 C 5
12 1' 1+ 1& 1* 14 16 17
)("0 )(30 )(C0 )(50 )(" )(3 )(C )(5
1'2 1''
P3' P3+
&.+. $as# "0" 30 385elay &s9 C0 C 50 5 !nterpretation# $here will be * pistons action in following sequence, "0" 30 385elay &s9 C0 C 50 5, in our tas. "fter piston 3 fully retracted, there will be &s delay before piston C start to extend. &.&. PLC 5esign and !mplementation a6 Group "ction "0 " 30 :roup
'
b6 Pro7ra##$/7
+
3 85elay &s9 C0 &
C 50
5
*
4
4. C$r%u$t De$7/
" required sequence was given# "0 " 30 3 85elay &s9 C0 C 50 5 Cascading method was used to design the sequence. (teps as following# a6 D$$0e t8e e9ue/%e $/to 7roup u%8 t8at /o etter $ repeate0 :$t8$/ t8e a#e 7roup.
5. Probe# a/a=$ a9 (eparate wrongly of the input ports ? output ports for table *.'. Connection was not woring at the beginning due to wrongly grouping, information was gathered and tried to group it out after reali@ed the mistae. Problem was solved after group members% discussion. b9 Aorget to put $2 after the delay. Bo delay effect happened, after multi trials, realised the mistae and amend the programme and rewrite it. (uccessfully run after $2 was inserted at the programme. ". Su##ar= o< t8e eper$#e/t 3y completing the three experiments, the pneumatic components and the PLC are nown and familiari@ed to students. Changes were made for each experiment to demonstrate to students of different way of activating the pneumatic components, where for the last practice, delay timer was also added. "fter the three practices, students have designed a circuit which to achieve the required sequences of different targets. Cascading method was applied to design the sequences, which is an easier method to build sequence groups and program the correct logic flow. (. Co/%u$o/ !n this experiment, we designed and implemented a PLC program for a given cycle of operations involved multiple cylinders. $hrough the experiment, we are now familiar with PLC control of pneumatic components used in building sequential circuits for industrial automation. -e are able to design and troubleshooting for simple PLC programs. -e learned that the PLC is very convenient for automation industry to do modification and implementation, since programs can be modified with very little hardware modification.
