Making a crossover cable

BundyRoy

Dedicated elf
Joined
Apr 9, 2014
Messages
1,026
I have a heap of cat5e cable left over from when I wired up the house network so I figured maybe it would be easier to make my own crossover cable to talk to LOR with DMX. Is it just a matter of buying the connectors putting the wires in the appropriate places and crimping the connector on. Is there anything I need to look for in a rj45 connector that will make connecting easier or are they all the same. Any tricks. I need to buy connectors and crimpers but figure the cheapo crimpers will do the job as I will probably only ever make a few cables.
 

AAH

I love blinky lights :)
Community project designer
Joined
Dec 27, 2010
Messages
3,446
Location
Eaglehawk
Using an inline joiner like http://www.jaycar.com.au/productView.asp?ID=YN8034 can easily be made into a lor/dmx crossover. These style of joiner just pop open and all you need to do is snip and rejoin the 4 relevant wires.

Coincidentally I'd planned on adding these connectors to my site (at a lot cheaper price) tonight as heaps of members use them for emergency cat5 joins or if swapping out dmx boards.
 

BundyRoy

Dedicated elf
Joined
Apr 9, 2014
Messages
1,026
Thanks Alan. I also saw on Davids website the other day that he sells the same thing already set up for crossover. Here's my logic. Let me know if it's flawed.

I need a 10m cable to go between my controllers. I currently have no spare cat5e cables so need to buy/make 1. I figured I could buy some cheap rj45 connectors and crimpers off ebay/elsewhere and make a cable for about the same price that I could buy one for (since I already have the cable). I also have the added benefit that it gets rid of some more stuff (that I already have had sitting there for ages) out of my shed.

Won't do it if it is harder to do than I imagine. Just wanted to make sure that all rj45 connectors are made the same and that there wasn't any tricks in choosing/buying them that I wasn't aware of.
 

BundyRoy

Dedicated elf
Joined
Apr 9, 2014
Messages
1,026
Thanks David and thanks for the link to the wiki.
 

AAH

I love blinky lights :)
Community project designer
Joined
Dec 27, 2010
Messages
3,446
Location
Eaglehawk
Well that puzzles me. I'd seen my own mistake and fixed the link. If you mouseover the link I pasted you will see the name and the link are 2 different ones.
 

BradsXmasLights

WiFi Interactive
Joined
Dec 23, 2010
Messages
578
Location
Brisbane, Australia
AAH said:
Using an inline joiner like http://www.jaycar.com.au/productView.asp?ID=YN8034 can easily be made into a lor/dmx crossover. These style of joiner just pop open and all you need to do is snip and rejoin the 4 relevant wires.

I'd recommend that rather than making an crossover cable.


My problem with non-standard RJ45 patch cables (and computer network crossover CAT5 cables for that matter) is when mixed with passive POE (power over ethernet) you can easily get power on to the wrong pins if you're not using a straight-through cable.


Trivial yes to mix up, but an easy mistake when in a hurry or tired.
 

fasteddy

I have C.L.A.P
Global moderator
Joined
Apr 26, 2010
Messages
6,645
Location
Albion Park NSW
Driver said:
AAH said:
Using an inline joiner like http://www.jaycar.com.au/productView.asp?ID=YN8034 can easily be made into a lor/dmx crossover. These style of joiner just pop open and all you need to do is snip and rejoin the 4 relevant wires.

I'd recommend that rather than making an crossover cable.


My problem with non-standard RJ45 patch cables (and computer network crossover CAT5 cables for that matter) is when mixed with passive POE (power over ethernet) you can easily get power on to the wrong pins if you're not using a straight-through cable.


Trivial yes to mix up, but an easy mistake when in a hurry or tired.
I agree that this could be a big issue for those who use and have POE equipment, but by far the majority would not have this. I always label my non standard cables anyway because nothing worse than getting them mixed up with your other cables and then having to fault find why something is not working and then finding out its a non standard cable you made in the past.
 

BundyRoy

Dedicated elf
Joined
Apr 9, 2014
Messages
1,026
Got myself a rj45 joiner at the local electrical shop today. I have pulled it apart. After looking at http://auschristmaslighting.com/wiki/DMX_Adapter_Leads it appears that maybe only 3 of the 8 pins are required to make it work (1 direction). Is the easiest way to turn the straight through connector into a crossover connector just pull out all the wires except the ones on 1, 2 and 7 on the upstream side and then slide the wires into the appropriate slots on the downstream end (4, 5 and 6 respectively). Or are the wires on pin 3 and 8 that go straight through without crossing over required.

I just thought it might save cutting and rejoining which seems like it might be hard in such close proximity to each other.

Thanks.
 

BundyRoy

Dedicated elf
Joined
Apr 9, 2014
Messages
1,026
Was watching a youtube video on how to put the rj45 connectors on cat5e cable last night. The bloke made the comment that cat5e cables need to b 0.5m long minimum and maximum of 100m. I can understand a maximum but what is the logic behind 0.5m minimum. Does there need to be a minimum amount of resistance for it to work or something else.

Reason I asked was I was going to make a very short crossover cable and then connect it to a long straight cable to make a long crossover cable. The short crossover length meant that the joiner would be inside the control box (out of weather) without excess cable pooling up in there. Can obviously make it 0.5m if I have to but just means there's excess cable in the box getting in the way.
 

AAH

I love blinky lights :)
Community project designer
Joined
Dec 27, 2010
Messages
3,446
Location
Eaglehawk
You're playing with RS485/DMX and there is no distance requirement other than a max total distance of 1.2km and a maximum number of boards connected of 32. The video is much more likely referring to ethernet and I can't say if there is a minimum distance but the max is definitely 100m.
 

BundyRoy

Dedicated elf
Joined
Apr 9, 2014
Messages
1,026
AAH said:
........a max total distance of 1.2km
If I can go that far I had better start making some plans for taking over the whole street then. :p

Thanks Alan. They were referring to ethernet but I didn't realise the signals were different.
 
Top