Hello all, I want to know can i multiplex RS-232 of AT89C51 to multiple serial slave devices supporting RS-232, if yes then how? & in this i think slave has no option to send data on its own, instead master has to poll all slave devices and check for data and any change whatever is there...?
Is there any method so that without polling i can use this multiplexing? Plz tell me all possible ways to multiplex RS-232 of AT89C51 with multiple slave devices?
can i multiplex RS-232 of AT89C51 to multiple serial slave devices supporting RS-232, if yes then how? transmit, yes, receive, not if any external device can transmit without being "asked".
I have seen implementations with analog switches (STINKS because of their lack of spike resistance) and with multiple MAX232(equivalents)
Erik
Some years ago I realized such a RS232 master-slave net. It wasn't my choice. Never again! Better use RS485 or CAN instead.
you can use a multiplexer the u can connect the controller RS-232 with many devices.
Hi. if you are into microcontrollers, some of them has built in TX/RCV for RS232. no need for level shifters.
Only if you connect on logic level (ttl) you can leave out a level shifter IC (bucket device?). But then you should'nt call that RS232, because that implies using + and minus negative voltages.
So you can definitly not connect a port chip without a levelshifter (max232) to an RS232 device, cause the chip is all ttl only ever and maybe cmos sometime.
So you can definitly not connect a port chip without a levelshifter (max232) to an RS232 device, cause the chip is all ttl only ever and maybe cmos sometime. the '51 was never TTL it has been issued in NMOS?, HMOS and now all are CMOS.