plc flowchart - 11.15

11.4SUMMARY

•Flowcharts are suited to processes with a single flow of execution.

•Flowcharts are suited to processes with clear sequences of operation.

11.5PRACTICE PROBLEMS

1. Convert the following flow chart to ladder logic. start

A on

yes

is B on? no

A off

no

is C on? yes

2.Draw a flow chart for cutting the grass, then develop ladder logic for three of the actions/decisions.

3.Design a garage door controller using a flowchart. The behavior of the garage door controller is as follows,

-there is a single button in the garage, and a single button remote control.

-when the button is pushed the door will move up or down.

-if the button is pushed once while moving, the door will stop, a second push will start motion again in the opposite direction.

-there are top/bottom limit switches to stop the motion of the door.

-there is a light beam across the bottom of the door. If the beam is cut while the door is closing the door will stop and reverse.

-there is a garage light that will be on for 5 minutes after the door opens or closes.

plc flowchart - 11.17

2.

plc flowchart - 11.18

plc flowchart - 11.20

3.

start

ST5

turn off door close

plc flowchart - 11.22

ST1

door close

L

MCR

plc flowchart - 11.23

plc flowchart - 11.25

ST8

door open

U

MCR