RS-485 issue while using half duplex communication

[jit_singh_tara]

rs-485 issue....

hi friends ... i faced a new problem in rs485 network ..
i am using half duplex communication....

1 master - two slaves

master sends data to 1 slave with first byte address , slave receives it shows the data on its port and sends back to master, now i change the address for slave 2, and send data but the second slave doesnt respond....


ofcourse it depends on how the program is written , please suggest a flow diagram for such an application ,

 

[laktronics]

Re: rs-485 issue....

Hi,
Did you ensure that the first slave has switched off its driver soon after its communication with Master is over?, it should be done.

Regards,
Laktronics

 

[Prabakaran]

Re: rs-485 issue....

In RS 485 Communication, the driver has to set , whether its in Transmitting state or Receiving state.


For Receiver Mode the EN should be Kept Logic Low.

For Transmitting Mode EN Should be Kept Logic High.

And For more than one Slave u should connect a Low Impedance at the Last Slave( Means u should Short the ( Signal A & Signal B) with the Low Value Resistance.