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Return to BlogConversion of RS232 to RS485 Interface
Posted Feb 09, 2012 at 10:03 am
Figure 1
The converter is designed for half duplex mode where the PC communicates with ROV using 2 wires from RS232 and RS485 interface.
The RS232 signals from/to TTL level is converted by the MAX232 while the MAX485 converts the TTL level signals to RS485 standard. The transmission mode of MAX485 is changed using the RTS line. The current state of the interface is indicated by the use of 2 LEDs. The whole circuit is constructed in a single layered PCB.
The device will be powered ON for testing after soldering all the components. A 5V value should be obtained from the pins 5 & 8 of MAX485 and pins 15 & 16 of MAX232 in order to produce a brighter red LED. The test proves the working operation of the converter with only a connection to PC using RS232 cable and running the Windows HyperTerminal or other similar program. A change in green LED should be noticed when clicking hook ON and hook OFF icons.
The real test is done by sending and receiving some data properly. This will require another device with RS485 interface and the two RS485 interfaces will be connected.
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2 years ago: the red LED looks like a watch tower while the other LED seems to be hiding from the enemy :)
2 years ago: where is the circuit diagram