Thanks Bob
Your extra input is very helpful. I now agree that both R5 and R6 are also completely extraneous and shouldn’t be there as well as R7, particularly if you’re aiming for a multi-node network. Both the official Arduino MKR485 shield and the excellent Waveshare Raspberry Pi 485 shield don’t have those pull-up resistors and make the 120R line termination resistor switchable.
All this board needed to be was a simple MAX485 breakout. Altronics supply the MAX485 IC itself which is the obvious alternative. As you said, this board is only suitable for either a simple point-to-point system, or during development.
It should be said that its not that hard to unsolder surface-mount components, so its fixable to a degree, but of course it shouldn’t require a soldering iron to make a purchased product fit for its own purpose.
Michael
