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Digital communication of Control Unit with a remote object

Digital communication of Control Unit with a remote object

A two wire line is used for digital communication between Control Unit and a remote object (pic.1, pic.2). The advantage of such communication is the PCP upshot between potentials of receiver and transmitter at the supply from different sources, and also high performance in terms of error probability. Current loop (pic.1) 10 mA supply from the receiver. Active resistance of line must not exceed 60 Ohm by using cable type FTP (UTP). Specific resistance of copper wire at 20° С p = 0.0175 Ом · мм²/м, Temperature coefficient of resistance – a = 0.4%/°С. Then maximal length of line at :

S – area of wire, мм².

Pic. 1. Circuit of digital communication of Control Unit with a remote object with the supply from the source of receiver.

Pic. 2. Circuit of digital communication of Control Unit with a remote object with the supply from the source of transmitter.

To increase length of line it is possible using the supply of loop from the source of transmitter (pic.2). At the the same basic values of elements length of line is multiplied in two times. Circuit on pic.1 and pic.2 for two-way communication requires two duplex lines. For two-way communication on one twisted steam it is possible to use a circuit represented on pic.3. The circuit carry out the double upshot between potentials of receiver and transmitter. During data communication a strobe is formed and a receiver analyzed the state of line at acceptance/transmission (pic.4).

Pic. 3. Circuit of two-way communication with a remote object.

Pic. 4. Circuit of two-way communication with a remote object.

added 23.12.07 23:30:09 | looked over 1780 times