Wednesday, May 21, 2014

RS485 Shield - Web/Arduino/Adam

I have purchased following RS-485 Shield.

RS-485 Shield

There was no manual ( just like I expected :( ), and shockingly schematic was not included.
Furthermore I couldn't even find the information about the manufacturer.  I sent an email to the address on the PCB ( ), and got the following:

RS-485 Schematic

This was unexpected.  Guess I should be thankful that they replied.


Although it is not shown on the schematic, there is a Jumper to allow the use of Soft Serial Port.  There are 3 Jumpers; however, Arduino Uno only has one Serial Port so we are going to use Soft Serial Port.

     RX-io    Set them for Jumper

Pin Settings:

  • Pin 3: RX
  • Pin 4: TX
  • Pin 2: DE

DE is only set to 'H' when transmitting, and at other times ( receiving ) DE is set to 'L'.  At other times Soft Serial is same as general serial, thus we don't have to care.

In Ethernet Shield, Pin 4 is used as SD_CS; however for now we are not using SD thus we don't have to worry about it.  If you really want to use SD, you have to move TX to somewhere around Pin 5 which involves cutting and soldering.  Very annoying...

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