Industrial Programmable Sequence timer

Abstract: - In most of the manufacturing industries the processes should be initiated one after another. Like as soon as first process completes second is initiated, second completes third is initiated and so on. And these chain reaction repeats in continuous loop. All the process have different time to complete. This may change depending upon different factors. For example,

1. In any chemical industry suppose it is required to dissolve any substance. This require specific time. Now as the property of substance (or even substance itself) changes then this time should be either increased or decreased
2. In pharmaceutical companies mixing of different substances makes desire medicine. As the time of this mixing process increased it will produce higher power medicine
3. In any textile mil as the fabric changes all the time setting should be changed to produce good quality clothes.

So there are lots and lots of such examples where there is a need of programmable sequence timer that triggers processes one after another for required time and this time can be programmed (set) for each process differently.

Here I have given one such application using micro controller (89C51) that has following features

• Initiates four processes one after another that runs on 230V AC supply
• Sets time for all processes from min 1 sec to max 60 sec (can be extended to any limit)
• Repeats sequence once or continuously as per requirement (so it can be used for batch production or for continuous production)
• LCD base display panel for better user interaction
• Potential free contacts (relay contacts) are given to connect any process / device
   
  click here to watch video of this working project on youtube

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System Block diagram: -

The figure given above shows major building blocks of programmable sequence timer. Let us understand function(s) of all of them one by one

Micro-controller 89S52: - It controls entire system by performing following tasks

• Accepts user inputs from push buttons to program sequence timer
• Switch ON/OFF all four processes one after another by energizing respective relay
• Shows different indication on indicators
• Displays different messages on LCD for time setting. It also displays remaining time for on going process

Push buttons: - There are five buttons and one sliding switch for user inputs

buttons & switches	function
start	to start sequence timer
inc time	to increase time set by 1 sec
dec time	to decrease time set bu 1 sec
enter	to enter set time value
emergency stop	to stop sequence timer in emergency condition
sliding switch	to repeat sequence once or continuously

Indicators : - Indicators indicates different events. They indicates which process is running currently, indicates inc time /  dec time event etc

Relay driver circuit: - It energizes or de-energizes the relays one after another as per the signal given from micro-controller. It provides enough current to relay coil to energize it. Because micro controller output is not enough to drive relay coil directly

LCD panel: - It displays various messages to guide user to program the sequence timer and to set timings for all processes like "set process 1 time and press enter", "press start" etc. Also it displays error message like "time is not set" if user doesn't follow the proper sequence. While sequence timer is running it displays remaining time of current process.

Relay(1 -4): - It is used to switch ON/OFF respective process as per the signal given by micro controller. All are NO (Normally open) type or may be CO (change over) type relays. They provides 230V AC supply to process through contacts so process runs till relay is in energized state.

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