[SOLVED] RS485 communications

I would need to use an RS-485 protocol to connect it with pc.My problem is that i confuse about how to do it?

I will need to RS485 module to sent data from one to other and the second to sent it via an rs232 module to pc?

IS this the case?

I would need to use an RS-485 protocol

Click to expand...

RS485 is not a protocol it is hardware layer.

You can use modbus protocol using RS485.

Search the net you will find lot of information.

Tom2 said:

I would need to use an RS-485 protocol to connect it with pc.My problem is that i confuse about how to do it?

I will need to RS485 module to sent data from one to other and the second to sent it via an rs232 module to pc?

IS this the case?

Click to expand...

First, make sure your PC has a serial port (this will be RS-232). Modern PCs no longer have them. If it does have a serial port, then you will need an RS-485 to RS-232 converter (RS-485<->RS-232). If it does not, then you can use a USB to RS-485 converter (USB<->RS-485) and not need the conversion of RS-485 to RS-232. You can go USB<->RS-232<->RS-485 with two converters but there are direct USB<->RS-485 available. The comment in #2 is correct. All of this conversion stuff applies only to the low level signalling levels. The higher level communication protocols must match.

To make it more clear,

I would use an RS-485 module (connected to microcontroller). The rs484 module is connected to wire (lets say 100m wire) on the other hand the wire is connected to another rs485 module which is connected to an rs232 module and finally the rs232 module is connected to the pc.

Is this ok?

microcontoller -->rs485 module --> 100m wire --> rs485 module -->rs232 module-->pc

Tom2 said:

To make it more clear,

I would use an RS-485 module (connected to microcontroller). The rs484 module is connected to wire (lets say 100m wire) on the other hand the wire is connected to another rs485 module which is connected to an rs232 module and finally the rs232 module is connected to the pc.

Is this ok?

microcontoller -->rs485 module --> 100m wire --> rs485 module -->rs232 module-->pc

Click to expand...

Yes on the PC side but the same rs485 module will not work on the microcontroller side. You will need an rs485 IC or some other way to connect to the microcontroller.

You mean something like the image bellow ??

HI,

If RS485 module is nothing but a TTL/CMOS to RS485 convertor then the microcontroller side will be O.K. And for the PC side just put an RS485 to RS232 converter and connect it to the PC's RS232 port. Your job is done.

485 IC must be use properly with 120ohm on both side and on one side Apin<-680 ohm ->+5V , Bpin <- 680ohm -> GND. Now 485 work stable! Advanced is if use 485 IC with embedded protection of bad termination + fault safe ... example SH65HVD3082