Actually RS-485 is 3 (THREE) wire interface as it has a common mode voltage on A and B lines. So there is a need to have a return path for the current induced by this voltage. And you will see that the device erminals are 3 screws: A, B and GND. The second thing is that you'd better name the data transmision lines as 'A' and 'B' rather than '+' and '-' as they are not always positive or negative. A and B naming convention will make and much more clearer and less tending to miswire.
Each device in the diagram is meant to be RS485 compliant, so they support the voltage/signal levels of RS485. This video shows how to connect RS485-compliant devices in a daisy-chained manner.
In RS232, there is a distinct Tx line and a distinct Rx line. Both of those lines use Ground GND line as a reference. RS232 is an example of full duplex transmission. However, RS485 works differently. Both + and - lines are used when data is being transmitted in either direction. It is a half duplex system. So in RS485, there is no distinct Tx and Rx lines. There is only + and -. If the host is RS485 compatible, then it to will have a + and - line and should be connected to the system in the same daisy-chain manner.
Actually RS-485 is 3 (THREE) wire interface as it has a common mode voltage on A and B lines. So there is a need to have a return path for the current induced by this voltage. And you will see that the device erminals are 3 screws: A, B and GND.
The second thing is that you'd better name the data transmision lines as 'A' and 'B' rather than '+' and '-' as they are not always positive or negative. A and B naming convention will make and much more clearer and less tending to miswire.
i'm confusing they has a A or B, + or -, D0 or D1. how to connect it when label is difference...
I want to know that in rs 485 terminal there is + & - and we are using it for feedback so for feedback what happens in + &-..
interesante
Thank you.
is it possible to convert two wire rs485 into four wire rs485
There is no such thing as 4-wire RS485. If it uses 4 wires then it is RS422. And yes, there are converters that will convert from RS485 to RS422.
Tks for this video.
You are very welcome.
How did you connect these devices to rs485?
Each device in the diagram is meant to be RS485 compliant, so they support the voltage/signal levels of RS485. This video shows how to connect RS485-compliant devices in a daisy-chained manner.
Emile Ackbarali txd of host should be connected to device signal + and rxd of host should be connected to signal-. Am i correct?
In RS232, there is a distinct Tx line and a distinct Rx line. Both of those lines use Ground GND line as a reference. RS232 is an example of full duplex transmission.
However, RS485 works differently. Both + and - lines are used when data is being transmitted in either direction. It is a half duplex system.
So in RS485, there is no distinct Tx and Rx lines. There is only + and -. If the host is RS485 compatible, then it to will have a + and - line and should be connected to the system in the same daisy-chain manner.
Nice explanation
Thanks Ratnesh.