Basic auto door program help

Hello,

I have a simple PLC program I hope someone can help me with. I have created my own ladder program and would simply like to make a comparision with someone elses

the following is the program:




THIS SIMULATION IS OF A DOOR APPROACHING AN ULTRA SONIC DETECTOR. THIS DETECTOR PUT THE DOOR MOTOR INTO FORWARD DIRECTION IN ORDER FOR THE DOOR TO BEGIN TO OPEN. WHEN THE DOOR REACHES THE UPPER LIMIT ON THE DOOR THE MOTOR MUST STOP. THE TRUCK WILL THEN CONTINUE ON ITS WAY THROUGH THE OPENING. THE DOOR WILL AUTOMATICALLY CLOSE ONCE THE BACK OF THE TRUCK FINISHES PASSING THE SECOND ULTRA SONIC DETECTOR. THE DOOR CLOSES BY PUTTING THE MOTOT IN REVERSE AND CONTINUES UNTIL IT REACHES THE LOWER LIMIT. CLICK ON THE PICTURE TO SEE A SIMULATION OF THE FINISHED WORKING PROGRAM.

there are alos three errors that must be avoided

ERROR 1

YOU WILL GET THE FOLLOWING ERROR IF YOU FAIL TO STOP THE MOTOR AFTER YOU REACHED THE UPPER LIMIT SWITCH
ERROR 2

YOU WILL GET THE FOLLOWING ERROR IF YOU PUT THE MOTOR IN FORWARD AND REVERSE AT THE SAME TIME.
ERROR 3

YOU WILL GET THE FOLLOWING ERROR IF YOU START THE MOTOR IN REVERSE BEFORE THE TRUCK HAS CLEARED THE DOOR AREA

I.E. THE BACK OF THE TRUCK MUST FINISH PASSING THE SECOND ULTRASONIC DETECTOR BEFORE YOU CAN ATTEMPT TO CLOSE THE DOOR.



thanks

Nice pictures, but where is the program?

Wel I was hoping that someone could create a program so i can compare it with mine. I have only drawn a program on paper I haven't downloaded the program to a plc yet.

I can do a quick JPEG sketch and put it up if necessary. however a more experienced programmer may have a solution that i could see. All the I/O are displayed on the pictures

thanks

Before you start programming, figure out your IO first. Your IO is NOT well defined, be specific, digital/analog, analog raw/engineering limit, etc..

2nd, do a detailed process description.

3rd, what kind of PLC/language?

We are NOT going to do your homework for you. Show us what you've already done, ask specific questions, etc., and we'll be glad to help, but don't expect us to do it for you...

wel basically:

the lorry drives towards the door. when the lorry hits I0.2 the driver stop and the door begins to open. once the door is open the upper limit I0.0 is activated and the (motor up operation) stops. the lorry then drives through the door. as its hood passes through the door it activates I0.3. however the door will not close (motor down operation) until the lorrys rear leaves the lazer dectecto (I0.3)

All signals a descrete i.e. on/off

INPUTS
I0.0 upper door limit
I0.1 lower door limit
I0.2 inlet lorry detector
I0.3 outlet lorry detector

OUTPUTS
Q0.0 Door motor open (up)
Q0.1 Door motor close (down)


as mentioned earlier there are a number of faults that will bring up alarms. these can be seen below.


thanks

Ok, now, what's the action of the IO?

For example, I0.0 upper door limit. Is it wired to be normall open or close and why?

Output, how is it wired? Latching circuit?

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I hope you get the idea why understanding the problem is 90% of the work. We can't do your homework, because, well, it can't be done without making a lot of assumption, which may or may not be the same assumptions you make.

The hardest, yet most important, part of any automation project is to DEFINE your system. Do NOT even start trying to write code until you know how it works, what the hardware components do and why, how it knows when it's done, how it detects faults, etc.

First, define your i/o. First ask what i/o you need - including how you interact with the system. Pushbuttons, limit switches, pressure/vacuum switches, photocells, etc, as inputs. Motors, actuators, etc., as outputs. You already have part of this - it looks like it was probably defined for you in your homework assignment. Now you need to add no or nc status on inputs.

(A bit of another note here: Are your lorry detectors ultrasonic or lazer?? You reference both. Each has its own set of concerns in real life - which you may or may not be concerned about for your homework...)

THEN -- AFTER you have your i/o figured out, you can start looking at how your system will function. Again, you already seem to have part of this, but not all of it. The best way to do alot of this is with a flow chart. Show each step sequentially. What is the "trigger" to transition to each step? What if it fails?

all switches are wired normally open (well that's what i applied to my logic) it didn't matter anyway i am only doing this for myself.