| Electronics > Projects, Designs, and Technical Stuff |
| Connectors for a RS485 network |
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| darrenb:
Hi, I have to put together a RS485 network on of all things a super maxi called InfoTrack. The network is to connect together a PLC, an Arduino and a Raspberry Pi using Modbus. I've got these all talking to each other now I just have to come up with the actual cabling and connectors. As I haven't been able to google anything off the shelf for this the best I have been able to think of so far is to use a 6 terminal terminal block at each connection point and mount this in a jiffy box. The six terminals are 1 to 6, 1 and 2 for the RS485 network coming in or if there is no other connection a 120 ohm resistor. 3 and 4 for the A and B for the device at this point (pi, arduino etc) and 5 and 6 for the RS485 network going out or another resistor. On the other side of the terminal block I'll just wire 1 and 3 together, 2 and 4 together and so on. For cable I am thinking of using 4 core twisted pair telephone cable. This should all work but I can't help thinking there must be a better way. Surely other people have had to create RS485 Modbus networks? |
| ledtester:
I think RJ45 (i.e. ethernet) cables are commonly used for RS485. Yeah it's overkill, but then you have future expansion possibilities and you also have a cable run which can be used for lots of other purposes. You might plan out your conductor assignments so that you can carry both RS485 and 100-baseT ethernet (which only requires 2 twisted pairs) at the same time. |
| darrenb:
I just realised that I also have to provide ground and maybe also a shield connector so my idea of using a 6 terminal terminal block won't work. Looks like I'll have to make up a pcb using either rj45 or rj11 connectors. |
| digsys:
I've used several methods over the years - including phoenix 0.15" 6/8W pluggable >> and now using CAT6 shielded PoE pinouts, which I also use for CAN Bus. In serious "factory" electrical connections though, I always go for fiber > fiber converters |
| vk6zgo:
The only RS485 network I've had anything to do with used 9pin "D" connectors. A bit clunky, maybe, but they have plenty of spare pins to play with! |
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