Several classic example explanation of Siemens PLC ( Including program) - - - - - -

The intersection traffic lights decorate the diagram below:

a, control requirements

1) A semaphore system controlled by a start switch, when start the switch, the light system began to work, when the start switch off, all the lights go out.

( 2) North and south green light and green light cannot at the same time. If light the lamp should be closed system at the same time, and immediately report to the police.

( 3) The red light keep 25 s. Things at the same time in the north and south of red light green light is bright, and maintain the 20 s. To 20 s, when the green light is shining, shining out after 3 s, at this point, the yellow lights, and maintain a 2 s. To 2 s, the yellow lights, red light. The red light goes out, the north and the south north and south green light.

( 4) What turns red, maintain 30 s. The green light to maintain 25 s, and shine out after 3 s. At the same time the yellow light, keep out after 2 s, when the red light, green light.

( 5) North-south, east-west lights above alternately repeatedly working state, the intersection traffic command, the temporal sequence as shown below.

2, PLC controller connection

3, define symbolic address

4, ladder diagram program

is shown in the following three floors elevator schematic diagram. Rise and fall of the lift is controlled by an electric motor; Forward when the elevator up and turns down the elevator down. Establish a call each layer switch ( SB1, SB2, SB3) , a call light ( H1、H2、H3） , one in place travel switch ( ST1、ST2、ST3） 。

control requirements:

1) Each layer of the call for push button switch, SB1, SB2, SB3 are instantly through effective

Is connected to the moment is open still valid) 。

( 2) The elevator casing way up only response to the rising call, descent way only respond to the call, any call is valid in the opposite direction, referred to as irreversible response. Specific action required, the following table.

( 3) Effective operation time between floors should be less than 10 s, or think there is a fault, automatic motor stalling.

A variety of automatic liquid mixing device of PLC control for three kinds of liquid mixing device, as shown SQ1, for SQ2 and SQ3 and SQ4 for liquid level sensor, liquid level drowned when switched on, the liquid A, B, C and mixture by electromagnetic valves YV1, YV2, YV3, YV4 control, M to stir the motor, the control requirements are as follows:

1. Initial state

device in operation, the liquid A, B, C, the valve closed, the mixture of the valve opening 20 s will be closed after emptying.

2。 Starting operation

press the start button SB1, device according to A given regular operation of the following:

1) liquid valve is opened, A liquid into A container. When the liquid level reaches SQ3, SQ3 press, closed A liquid valve, open the liquid valve B.

2. When the liquid level reaches for SQ2, closed liquid B valve, open the liquid valve C.

3. When the liquid level reaches SQ1, close the liquid valve C, stir in motor began to stir.

4. Stir in motor work after 1 min to stop stirring, mixing liquid valve open, start out mixed liquid.

5. When the liquid level drops to SQ4, SQ4 by on getting off, again after 20 s, to empty container mixture valve closed, begin the next cycle.

3。 Stop operation

press the stop button SB2, to mix the current processing after the completion of operation, to stop operations ( Stop at the initial state) - > 1 order go out. - > 8 order go out. After all out, stop light 2 s, start again from scratch, the cycle. Reference ladder diagram program:

design program, make two cylinder action sequence, the following order: A1B1B0A0.

( A) Pneumatic circuit

2) Displacement - Step figure

3) Type I obstacle signal analysis

4) PLC wiring

5) Define symbolic address

6) Ladder diagram program

vending machine PLC control

vending machine diagram as shown in the figure below, the job requirements are as follows:

1. This vending machine can be put into 1 yuan, five yuan or ten yuan coin.

2。 When the input more than 12 yuan coin, soda button indicator; When the input of hard

COINS for more than 15 yuan, the total cost of soda and coffee button indicator is on. 3. When soda button lights, soda button, will automatically stop after soda out of 7 s; this time, soda, lights flashing. 4. When the coffee button lights, press the coffee button, will automatically stop after coffee out of 7 s; this time, coffee indicator lights flashing. 5. If the amount of money needed to put in a coin worth more than button ( Soda water 12 yuan, 15 yuan coffee) Change, change indicator, said action, and exit the extra money. Reference answer:

more about Siemens PLC fascinating reading:

Siemens PLC model selection _ Siemens PLC controller model description

Siemens PLC controller wiring diagram physical figure

_ Siemens PLC of Siemens PLC data type communication

Siemens PLC program download step

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