RS232 electricity theft Technology

The power output pin is not defined in the EIA-RS232 standard, so the RS232 interface can not find the power output pin, can only indirectly obtain the power from other RS232 pins. The most direct method is to use pin7 and pin4 pins, which are sufficient to drive mos ic chip devices such as cd4093 and lm324. In addition, you can use the following methods to obtain power from the Tx and Rx pins.

TX and Rx are positive and negative changes in signal transmission. The diode D1 and D2 in the figure can obtain a certain amount of energy from RX and Tx for subsequent circuit use. Because direct I/O in this article does not use TX or RX to transmit data, only pin7 and pin4 are used for RS232 power theft. The circuit diagram is as follows:

 

A better method of electricity theft is the combination of the above two methods. The circuit diagram is as follows: