29-11-2012, 12:18 PM
Industrial Switching With Real Time Feedback
1 Switching With Real.pptx (Size: 163.21 KB / Downloads: 32)
Project Definition
Wireless Industrial device control (switching) system can be used to switch on or off four devices that are connected to the system with real time feedback.
When these devices are switched on or off the status is shown on the control panel.
It is the feedback of the base unit to which the devices to be switched are connected.
There are two main units:
1.Control or Command Unit :It has four switches on the front panel with which devices can be controlled.
2.Switching or base unit : The devices to be switched are connected to it. This section has two ways radio link connected to the other unit which is the command or the control unit. Each switch has a corresponding LED aside it which shows the status of the device that is controlled by that particular switch.
Microcontroller:
Controller used here is the P89V51RD2 belonging to the 8051 family.
Heart of the entire circuit.
Decode the received signal from control unit and send it to relay based circuitry.
Furnished with a 12MHz crystal as a source of clock pulses.
Four data out pins of the decoder 1 are directly connected to the lower nibble of the port 1.
The VT terminal has also been utilized to interrupt the controller.
The software installed in the controller is such that whenever an interrupt arrives at the controller, it reads the data on the lower nibble of the port 1.
After that the output port pin corresponding to that data is complemented.
This will reflect in switching on or off a corresponding device.
A bank of four relays has to be driven from the outputs of the controller.
Criteria for Choosing Microcontroller
The first and foremost criterion is that it must meet the task at hand efficiently and cost effectively.
Speed
Packaging
Power Consumption
Cost per unit
Easy to develop products around it.
Its ready availability in needed quantities both now and in the future.
HT12E(Encoder) :
An encoder is a device, circuit or transducer that converts an information from one format or code to the another for the purposes of speed and security.
Each address/data input can be set to one of the two logic states.
The programmed addresses/data are transmitted together via an RF or an infrared transmission medium.
This cycle will repeat itself as long as the transmission enable is held low.
RF Transmitter/Receiver :
All the receivers and transmitters used in the system are of same type.
They are given numbers due to the fact that a full duplex mode of communication has been realized in the working of the system.
The first part of the link which comprises of and transmitter 1 at the control/command unit and receiver 1 at the switching/base unit, which is used to send and receive commands from the control unit to the switching unit.