plc help

[jerry859]

I am wanting to program logic in an AB plc and need a little help since I am fairly new at this task. I have 2 conveyor motors that I am wanting to turn off once I receive an input from a limit switch that it is made. 2 of these limit switches will be for conveyor A and 2 will be for conveyor B. Once I have an input I want the specified conveyor to stop, sound a buzzer and light up a truoble light( both outputs) for each conveyor. After the problem is corrected I want to use a pushbutton to reset the buzzer and light. Next I need to restart the conveyor. Any help will be greatly appreciated. Thank you.

 

[TConnolly]

Greetings Jerry and welcome to the forum.

Is this a lab assignment for a class? I looked at your other post made a couple of days ago and it looks like you are a student. If so you've come to the right place for help... provided you show a little effort. We love to tutor students who show they are eager to put forth the effort to learn.

First, please tell us which AB PLC you are using. Then list the inputs (limit switches, buttons, etc), whether the switch is normally open or normally closed, and their PLC address and their function. Then list the outputs (lights, buzzers, conveyor motors, etc), their address, and their function. At this point I think you'll have a pretty good idea what to do next but if you'll do that then we're happy to help.

 

[jerry859]

Micrologix 1200 plc. I will have 6 inputs. The 4 LS will be 1/0001-1/0004. The 2 reset PB will be 1/0005-1/0006. The inputs will all be NO. The 4 outputs will be the lights, buzzers, and conveyor motors. The lights will be 2/0001-2/0002, the buzzers will be 2/0003-2/0004, the conveyor motors will be 2/0005-2/0006. The conveyors will be labeled A and B. There will be 2 LS assigned to each conveyor with a seperate light and buzzer for each. Each conveyor will also have an assigned reset pb. Once either LS is made for a particular conveyor, a light and buzzer will be turned on and that conveyor will be stopped. Once the LS is reset, the reset pb can be pressed to reset the buzzer and light. Once everything is cleared the conveyor can be restarted.

 

[James Mcquade]

jerry859,

may i suggest that you do the following.
1. draw a sketch of your system, include the sensors and motors.
2. write out what you want the system to do.
3. assign the i/o.
4. draw the ladder diagram out on paper, or type it in.
as you look at your logic, questions will come up.
post what you've done, and we'll make suggestions.

regards,
james

 

[TConnolly]

OK, so lets convert this to a statement.

Conveyor_Motor_A (O:2/5) runs when the Reset_PB_A (I:1/5) is pressed and not Limit_Switch_1_A (I:2/1) and not Limit_Switch_2_A (I:2/2).

Once the motor is started by pressing the Reset_PB_A it should keep running after the button is released until one of the limit switches turns on. This is called seal-in logic and it is usually done by OR-ing the output with the start input (reset button). Now taking the statement above and the seal in we can create a boolean equation:

((I:1/5 OR O:2/5) AND NOT I:2/1 AND NOT I:2/2 = O:2/5


Now lets make a statement for the light and buzzer.

Light_A (O:2/1) runs when Switch_1_A (I:2/1) and not Limit_Switch_2_A (I:2/2) and not Reset_PB_A (I:1/5). See if you can make an equation for this statement. You might want to use seal-in logic as above to keep the lights on until reset)

Buzzer_A (O:2/3) runs when Light_A (O:2/1) is on.
Convert this to a boolean equation.

Conveyor B is the same except that the addresses are different.

Make a try at converting those statements and boolean equations to ladder logic. Post your work here as a picture or if you have the programming software you can zip the .RSS file and attach it to a post.

 

[tracer]

??what are the 2 kimit switches for?