Thursday, August 8, 2013

RS-485 Communication testing with MAX485

As we know about RS-232 communication protocol, I'm going to try RS-485 communication between two nodes. RS-485 can support multiple slaves and mostly used in industrial applications with high separation distance between nodes. I recently got 10pcs of MAX485 IC from ebay for $1 which is a RS-485 transceiver. I also got  USB to RS-485 convertor based on CH430 + MAX485. I'm using another USB-UART convertor based on PL2303 for this test setup. So, I have two USB-UART chips connected using two MAX485 ICs in between,which provides the RS-485 communication.

My test setup according to MAX485 datasheet.
(Image extracted from datasheet)

As MAX485 is half duplex, I have to use one as TX with following setup. I'm using my USB-RS485 adapter as  RX and there is no need of manual setting as RX.

My TX setup on breadboard:

My RX setup, the one is right is USB-RS485 convertor:

Test results :


  1. Hi,
    It looks like the diagram need to be corrected. The RO must be connected to Rx and the DI connected to TX, right?

    1. Agreed. I've been working with these lately and RO is Receiver Out, DI is Data In (connected to the chip/converter Tx).

    2. Sorry guys, just saw the mistake, I'll correct it, thanks for pointing it out :)