Application Program; Example: Carousel Indexer - Mitsubishi Electric FX Series Training Manual

Application Program

Application Program
4.2
4.2.1

Example: Carousel Indexer

The following application program will be used to illustrate the creation of a simple program
using the tools of GX IEC Developer.
Operational Sequence
Momentarily operate foot switch to index carousel.
Carousel rotates – 'In-Position' sensor turns OFF as carousel begins rotating.
'In-Position' sensor turns ON when carousel reaches index position.
Assemble product
Repeat process (Go back to
MELSEC PLC I/O List:
MELSEC PLC I/O List:
X0:
X1:
Y0:
There are a number of issues that must be addressed when designing a PLC program for the
above application. Using a standard Start / Stop circuit is not possible without modification due
to the following difficulties:
b The foot switch may be operated at random. Once activated, it may be possible for the
operator to forget to release the switch which may cause the table to continue to rotate past
its index position.
b Once "In-Position" X1 operates, it remains on, thus the table is prevented from re-indexing.
The design must therefore contain interlocks to prevent miss-operation as described above. An
alternative approach to the design would suggest the use of 'Pulse Transition Logic' by means of
the IEC or MELSEC "Edge Triggered" configurations.
4 - 4
Proximity Switch Proximity Switch
"In Position"
"In Position"
X1
X1
Foot Switch
Foot Switch
"Index
"Index Carousel"
Carousel"
X0
X0
Foot Switch
In Position
Motor Drive
.)
Drive Motor
Drive Motor
Y10
Y0
M
Building a Project
Product
Product
Assembly
Assembly
Station
Station
MITSUBISHI ELECTRIC