PLC ladder diagram using Rslogix 500 ( Micrologix 1500 Allen Bradley)

Hello, I am having some problems and I am wondering if I can get some guidance. I will explain the process I am trying to achieve. I am trying to determine if a product is a pass or a fail ( using image processing which is done by a camera connected to my laptop ) therefore, I am using a conveyor to place the item on and a sensor to stop the item at some desired position so that I can start image processing and then based on the result I would either get a PASS or a FAIL. the ladder diagram is as follows:
if a push button is pushed for 10 seconds or so an ALARM takes place so that the area is cleared also a 10 seconds timer takes place before moving the belt.
once the sensor is triggered and the belt is moving unlatch the output and stop the belt. if the belt is stopped and the sensor is on start image processing.
based on which if it is a fail start an alarm and a 10 seconds timer then move the belt. if it is a pass just move the belt.
I tested my ladder diagram and im not getting the desired answers. I know I have a mistake somewhere can't really figure it out..

Please find enclosed the ladder diagram

Questor22 said:

I tested my ladder diagram and im not getting the desired answers.

Click to expand...

Can you please elaborate?



-Eric

Of course. Let's say Start push button is pressed for 10 secs it will make an alarm and a timer that goes to 10 secs which will latch the conveyor ( moving ). now if the sensor is triggered it will unlatch the conveyor ( now it is not moving ). then it start image processing. so far no problem, however now when I receive a result from one of my inputs say the PASS bit I would expect the conveyor to latch on and move according to rung 0001 which is not the case

When the 'PASS' bit turns on, it will latch the 'MOVE BELT' output. The problem is that it will immediately get UN-latched by rung 2, because the 'SENSOR TRIGGERED' input is on.

One solution would be to make the 'SENSOR TRIGGERED' input turn on a 'one shot' (look up ONS or OSR in the programming manual), and use that to stop your belt. Then it won't be on when the 'PASS' bit latches the output.

I'll add one more thing... Your 'STOP' button will NOT stop the conveyor! You should probably make it unlatch the 'MOVE BELT' output, or something similar.



-Eric

Thank you.
I will look into it and let you know how it went.