RS-485 Comms cables - really that special?

LandyMan

LandyMan

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Hi all
So in the final stretch (hopefully) of building our trolleys, I am studying the battery and inverter manuals, to make sure all are configured and set correctly.
The batteries need RS485 comms cables for Serial configuration (awaiting confirmation if these were shipped with the batteries).
However, in the meantime I have been looking around, and it appears CAT5/CAT6 will also work.

Any experience/advice/guidance wrt replacing the RS485 cables with CAT5/CAT6?

Thanks
 
LandyMan said:
Hi all
So in the final stretch (hopefully) of building our trolleys, I am studying the battery and inverter manuals, to make sure all are configured and set correctly.
The batteries need RS485 comms cables for Serial configuration (awaiting confirmation if these were shipped with the batteries).
However, in the meantime I have been looking around, and it appears CAT5/CAT6 will also work.

Any experience/advice/guidance wrt replacing the RS485 cables with CAT5/CAT6?

Thanks
Click to expand...
RS 485 is simply the communication protocol over the wires, the wires itself does not matter.
 
BTW, if you're looking for inexpensive comms cable, I accidentally found some at one of those cheap electronics shops run by Muslims. I was looking for some Cat5E cable and they "had some". The price seemed pretty good at the time (before I found myself a nice half a kilometer spindle). Anyway, so they had some "Cat 5" cable, a 40 metre patch, and I bought it, except, of course, it wasn't Cat5, it was fake. It's just an 8 core cable without any twisted pairs, and the wiring seems pretty low quality (thin and seemingly aluminum), so the Ethernet transmission speed is only 100Mbps over it. Nevertheless, such cheap cabling can make for a solution for other applications, such as RS232, RS485, etc, etc, if you're not too concerned about quality.
 
LandyMan said:
Hi all
So in the final stretch (hopefully) of building our trolleys, I am studying the battery and inverter manuals, to make sure all are configured and set correctly.
The batteries need RS485 comms cables for Serial configuration (awaiting confirmation if these were shipped with the batteries).
However, in the meantime I have been looking around, and it appears CAT5/CAT6 will also work.

Any experience/advice/guidance wrt replacing the RS485 cables with CAT5/CAT6?

Thanks
Click to expand...
Yep, 485 is just a 2-wire, positive and negative, low-voltage loop. You can practically use anything for it. CAT5 works well. You could switch to shielded CAT6 is you're doing a very long run.
 
The main cable requirement for 485 would be that the data lines be a twisted pair.
 
Blu82 said:
What would the minimum requirement be for wiring harness carrying 485 be then?
Click to expand...
The environment dictates the requirement. Most industrial cable aren't twisted pairs. I'm not saying there is no benefit to using twisted pairs, but there are a few things that can go wrong no matter how twisted you are :notworthy:

Things to consider are pretty much just the wire gauge for the distance you are covering. Short 'patch cable' runs, like in OP's use case, there really isn't anything to worry about and will probably have stable comms without issues.

My personal go to's in this order for covering some distance (eg. 20m plus):
  1. A properly grounded site/equipment.
  2. Shielded cable with a ground-wire attached to above said properly grounded equipment.
  3. Staying away from AC as much as possible.
 
Last edited:
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