20-09-2017, 03:56 PM
In most modern manufacturing and processing industries, there is complete industrial automation through sophisticated hardware and software such as programmable logic controller (PLC), distributed control system (DCS) and monitoring and data acquisition (SCADA) . Integrated systems based on microcontrollers play an important role in industrial automation. One of these widely used systems is the programmable timer. The main applications of the programmable timer are:
1. Start the process after the desired time
2. Turn on / off the process after a predetermined time
3. Provide a delay between processes
4. Application of the input to the control system in open loop type on / off
Depending on the process requirement, the programmable timer can be set. As the time period expires, the timer will activate or close the process. Previously there were mechanical timers that used mounting gears (same as wall clocks) and mechanical contacts. But the problem with these was that because of the mechanical parts and movements, they were not durable. Electronic timers have become very popular as they have more functionality and a longer life.
A simple electronic timer can be done using a single IC 555 in monostable mode that can activate / deactivate the process after the desired time. In addition, in the chain process (where the end of the first process begins the second process and so on), a series of such monostable blocks can be used to make a sequential timer. But these circuits do not include additional features such as digital display, system fault indication, remote operation and alarms. Since the accuracy and precision of these timing circuits depend on the value of the resistor-capacitor components that may deviate, we may not get the exact and precise time. To improve the programmable timer to generate precise time and additional features, microcontrollers (integrated controllers) with peripheral devices are used.
1. Start the process after the desired time
2. Turn on / off the process after a predetermined time
3. Provide a delay between processes
4. Application of the input to the control system in open loop type on / off
Depending on the process requirement, the programmable timer can be set. As the time period expires, the timer will activate or close the process. Previously there were mechanical timers that used mounting gears (same as wall clocks) and mechanical contacts. But the problem with these was that because of the mechanical parts and movements, they were not durable. Electronic timers have become very popular as they have more functionality and a longer life.
A simple electronic timer can be done using a single IC 555 in monostable mode that can activate / deactivate the process after the desired time. In addition, in the chain process (where the end of the first process begins the second process and so on), a series of such monostable blocks can be used to make a sequential timer. But these circuits do not include additional features such as digital display, system fault indication, remote operation and alarms. Since the accuracy and precision of these timing circuits depend on the value of the resistor-capacitor components that may deviate, we may not get the exact and precise time. To improve the programmable timer to generate precise time and additional features, microcontrollers (integrated controllers) with peripheral devices are used.