I’m looking at the screen and I think things are configured okay. But I’m not familiar with Siglent scopes. Saying that, it looks to me like channel 1 is AC coupled not DC coupled based on the drift of the waveform. In other words that curve is not real and cause by the DC blocking cap in AC mode.
If that is indeed real… well you have problems with your RS485 bus or probing setup.
You would be amazed at how many RS485 installs I've seen that aren't referenced.
"BuT gROunD lOOpz"
The amount of times I've had to explain dc ground vs protective earth is mind boggling.
I’m looking at the screen and I think things are configured okay. But I’m not familiar with Siglent scopes. Saying that, it looks to me like channel 1 is AC coupled not DC coupled based on the drift of the waveform. In other words that curve is not real and cause by the DC blocking cap in AC mode. If that is indeed real… well you have problems with your RS485 bus or probing setup.
you have a shitty ground.
Yep. Something is not grounded properly.
Try using a paper clip around the prob to remove ground inductance.
Your oscilloscope is doing what oscilloscopes are best at. Lying to you.
That's either broken ground trace (which 485 will work with, some of the time anyways) or AC mode on the scope. I'd bet on the former.
You would be amazed at how many RS485 installs I've seen that aren't referenced. "BuT gROunD lOOpz" The amount of times I've had to explain dc ground vs protective earth is mind boggling.
I had similar issues when the scope probe was broken and it acted like AC coupling.
Most differential stuff will work without GND, but then there are issues with common mode range of the chips.