TL/DR: author tried to run RS485 cable next to 1000V DC line, could not solve EMI issues, did no real diagnostic (except cable swap), gave up and went to analog.
Also tons of AI-generated slop. Fr example the "shields do not protect from capacitive coupling" part is absolutely nonsense. Ground reference jumping, within reason, is totally OK for RS485. The disturbances do not accumulate. While DC/DC converters _do_ have fast switching transients, those are blocked by input/output capacitors and do not appear on the cables, unless those converts are defective.
Also, the title seems to lie. Author tried original cable and one more "OEM cable", and that's it.
Hard disagree, if you have ever actually dealt with this stuff, you would know that it's all mitigation. Hardware isn't the binary world of digital stuff. Shielding is a filter with a curve and long wire runs make every aspect worse. Its couples capacitively with external signals as much as it capcitively couples with your internal signals. Which in a way means the shield can act as a "stepping stone" to your signal. I have even seen a situation where removing shielding fixed the problem (albeit at a bit higher voltage). In the textbook shield is perfect ground, in reality its a mess of RLC components.
Also switching transients/switching noise are mitigated by capacitive decoupling (and chokes), not "blocked". If only it was that easy, hah
What OP could have tried is putting some ferrite beads on the signal lines to eat some of the transients. Or put another shield around the signal lines as they pass through the building and ground that with it's own wire to the circuit ground. Or put TVS diodes on the signal lines. Or switch to current signals, like they did.
TL/DR: author tried to run RS485 cable next to 1000V DC line, could not solve EMI issues, did no real diagnostic (except cable swap), gave up and went to analog.
Also tons of AI-generated slop. Fr example the "shields do not protect from capacitive coupling" part is absolutely nonsense. Ground reference jumping, within reason, is totally OK for RS485. The disturbances do not accumulate. While DC/DC converters _do_ have fast switching transients, those are blocked by input/output capacitors and do not appear on the cables, unless those converts are defective.
Also, the title seems to lie. Author tried original cable and one more "OEM cable", and that's it.
Worst kind of AI slop.
Hard disagree, if you have ever actually dealt with this stuff, you would know that it's all mitigation. Hardware isn't the binary world of digital stuff. Shielding is a filter with a curve and long wire runs make every aspect worse. Its couples capacitively with external signals as much as it capcitively couples with your internal signals. Which in a way means the shield can act as a "stepping stone" to your signal. I have even seen a situation where removing shielding fixed the problem (albeit at a bit higher voltage). In the textbook shield is perfect ground, in reality its a mess of RLC components.
Also switching transients/switching noise are mitigated by capacitive decoupling (and chokes), not "blocked". If only it was that easy, hah
What OP could have tried is putting some ferrite beads on the signal lines to eat some of the transients. Or put another shield around the signal lines as they pass through the building and ground that with it's own wire to the circuit ground. Or put TVS diodes on the signal lines. Or switch to current signals, like they did.
The proper term is AI/DR
[flagged]