Hi.
Can i send 4 rs485 signals in only one ethernet CAT5e wire?
Thanks in advance
In general - yes, the trick might be to provide the required ground line as well.
It may also depend on what kind of distance you’re trying to cover.
What’s your application look like, can you do a simple diagram?
For a simplex setup with a low baud rate (<1Mbs) than it is okay. I have used Cat5e for DMX lighting (short runs) and it worked fine. The only ‘but’ is shielding.
The RS485 interface standard does not specify a ground wire, but such wire is needed to provide a return path for common mode currents and consequently reduce emissions. It may be possible to operate the RS485 loop without a ground wire, but such systems may radiate high levels of EMI.
A shield limits coupling of external interference and noise onto the bus. Generally the shield should be connected to the chassis ground (installation ground) at one end of the cable. In case of ground potential differences between nodes (common in industrial locations) this arrangement prevents the flow of DC ground loop currents in the shield. Ground loop currents flowing in the shield will induce noise in the communications cable.
RS485 nodes can generally tolerate from -7V to +12V of common mode voltage.
Hope this helps.