Connectors are not part of RS-485 standard.
As the old joke has it, standards are so good everyone should have their own:
Here are several conflicting specifications for half-duplex RS-485 on D-shell 9-pin connectors:
- Modbus uses pins 5 and 9 and 1. Standard, section 3.5
- Digi uses 3 and 9 and 5. Ref
- Virtual Serial Port uses 3 and 7 and shell. Ref, fig 3.9
If there's something common in your industry, use that. Otherwise I'd suggest Modbus, because "RS-485 on DE-9 per Modbus standard" is easy to say, easy to check, and buy ready-made cables for.
Answer from jonathanjo on Stack ExchangeConnectors are not part of RS-485 standard.
As the old joke has it, standards are so good everyone should have their own:
Here are several conflicting specifications for half-duplex RS-485 on D-shell 9-pin connectors:
- Modbus uses pins 5 and 9 and 1. Standard, section 3.5
- Digi uses 3 and 9 and 5. Ref
- Virtual Serial Port uses 3 and 7 and shell. Ref, fig 3.9
If there's something common in your industry, use that. Otherwise I'd suggest Modbus, because "RS-485 on DE-9 per Modbus standard" is easy to say, easy to check, and buy ready-made cables for.
No, because the RS-485 standard itself does not define any connector or any pinout, among many other things that the standard does not define.
Also a DB9 connector does not exist, but I will assume you mean DE9 connector.
However, many other standards that build on top of the RS-485 standard do define a connector and a pinout. So this means there can be many different pinouts used by many different standards on DE9 connector.
Just pick a pinout that is commonly used, standard or non-standard.
Many other differential buses that don't use RS-485 but still have rather compatible cabling and might use a DE9 connector in practice do exist.
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Connectors are not part of RS-485 standard.
As the old joke has it, standards are so good everyone should have their own:
Here are several conflicting specifications for half-duplex RS-485 on D-shell 9-pin connectors:
- Modbus uses pins 5 and 9 and 1. Standard, section 3.5
- Digi uses 3 and 9 and 5. Ref
- Virtual Serial Port uses 3 and 7 and shell. Ref, fig 3.9
If there's something common in your industry, use that. Otherwise I'd suggest Modbus, because "RS-485 on DE-9 per Modbus standard" is easy to say, easy to check, and buy ready-made cables for.
Answer from jonathanjo on Stack ExchangeI'm developing some automation equipment that will go into an overseas factory. The factory would like to communicate with the equipment and I'm recommending to do so via RS485; however, I can't seem to find any standard or best-practice connectors and/or pinouts. Seems like DB9 or RJ45 would be good options, but searching online shows a variety of pinouts. I'd imagine that you'd need adapters for different pieces of equipment from different manufacturers to talk to each other. Is that they way it is, or am I overlooking a standard? Thanks!