50 transceivers all with 120 ohms? That's 2.4 ohms across the bus lines. How can that work?Are they actively terminated perhaps?
The signal should be above +/-400mV if I recall, and bellow +/-200mV it is undefined. The special fail safe transceivers... wait is that why it works? Yep, the MAX3085 is one of the failsafe parts, it sees everything above -50mV as a HIGH. Are there resistors between A and +5V as well as between B and 0V. I guess that would do it.What I am doing is just as outlandish, I turn everything off to send a HIGH so on the pair, 0V is a HIGH bit and -3V is a LOW bit. The transceivers seem to be cool with the HIGH (so to speak) and so is the battery.
I was able to put them to work on breadboard.
Aside 2: Seems bl00dy stupid to me that the unit has the resistor hardwired in so all of them are terminators unless you break it. Putting an smd resistor back is beyond my ability. A jumper would have made life a lot easier, even if it upped the price a wee bit.
This are prototype modules, is normal to have those resistors.If moving to a production environment:1) Use your own RS485 implementation and diagram2) Adapt the modules
Not yet, but i will when doing the final tests.
i am documenting the entire project on another post.
Righto. But meantime I assume it's working with the terminator in place on the middle board?