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I connect 2 PIC by RS485 using 2 max485 for level conversion. and I use rs232 library to send and receive data. I also use a PIC's digital output to drive max485 pin number 2 and 3 together. to set always device hearing (output 0). and only when this output is high to transmit.
up to my knowledge RS232 / RS485 is deffered the way the signals are deffined.
The RS 232 signals are represented by voltage levels with respect to ground.
In RS 485 Each signal uses one twistedpair Differential voltage transmission.
Any UART chip / MCU standard UART works fine with RS 485 transciever.
Only problem is when you are connecting to a desktop PC. Here you need RS 232 to RS 485 converter. Some /All converters needs RTS/DTR to be asserted for a while before transmission.
Reffer to lvr serial port page for detailed info about serial ports and
RS 232/422/485 communications. Link is given below **broken link removed**
16c550 chip and your rs232 library just works fine.
You can connect, but RS485 is half-duplex (RS232 is full duplex), then you have to select when you'll transmite and receive. Use a SN75176 of Texas and connect it like above:
TX(16c550) at D(pin 4) (SN75176)
RX(16c550) at R(pin 1) (SN75176)
DE of SN75176 enable transmiter
RE of SN75176 enable receiver
generally they are connect together because it isn't full duplex, then you have to decide how connect RTS and CTS, because it isn't a good idea use DE and RE as like RTS and CTS because they aren't differential (and only input), and for long distances you can has problems. I don't know how 16c550 device works by I think you can use RTS or DTS for control DE and RE together.
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