Post on 07-Apr-2018
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A project on the control of an elevator
using PLC
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To design and simulate the working of an elevator
servicing a four story building
To develop logic for the operation of the elevator To simulate the working of the logic in a suitable
programming software like C++
To implement the hardware for the level translation of
PLC to interfacing card voltage and vice versa
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Process
Elevator starts off at the ground floor
Calls from various floors are taken in as input
Calls answered as elevator moves up Elevator reaches top floor
Calls answered as elevator moves down
Elevator reaches ground floor
Process repeats
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Process Chart
Calls
Groundfloor
UP callsanswered
Top floor
DOWNcalls
answered
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Modules UP cycle
DOWN cycle
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PC Implementation Choice of C++ based on following factors
Simplicity and familiarity
Modular function based approach
Number comparison functions
Ease in duplicating and assigning variables
Timer functions
Counting functions
Logic can be scaled to PLC level
Relatively easy debugging
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The Code Modules
Function based
Four user defined functions One main function
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Modular Approach Main() function
Check_call_up()
Check_call_down() Up_cycle()
Down_cycle()
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Logic and Code Header files added are as follows
#include
#include
#include #include
Global Variables defined are as follows int cur_pos = 0;
int calls[4];
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Check_call_up() Checks for up calls
void check_call_up()
{
int t;
for (int i=cur_pos;i
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Check_call_down() Similar to check_call_up()
void check_call_down()
{
int t;
for (int i=cur_pos;i>1;i--)
if (calls[i]==0)
{
cout
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Up_cycle() Status display messages
Movement of elevator
Check for call Door status message
Check for new calls
Repeat cycle
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Level Translator Circuit Elevator interface consists of ICs of 3.5 to 5V high and
0 to 2.5V low
PLCs work at a voltage level of 24V high and 0V low Step down part mainly consists ofoptocoupler ICs
Step up part is a TTL circuit
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Applications of elevator Transport of people from floor to floor. Eliminates the
need for stairs or escalators.
Carrying loads. Can be used as a scaled down and inexpensive version
of a crane or lift. Control via remote location for liftingof heavy goods.
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Thank You