Data Bus Hub, 568A vs 568B, patch cables

[AceCannon]

I plan on using some of Monoprice's pre-made cat5e patch cables, which I understand are wired using 568B. The Data Bus Hub documentation instructions state to terminate the cat5 using 568A. Since the only difference is the orange and green pairs being reversed (and those are the leads that are shorted together at the data bus devices anyway), can't I use either termination standard with impunity?

I was potentially going to connect the DBH in my closet to input expanders, etc using some of these patch cables with one end cut off. .

Does this question make sense? I'm not sure I have worded it very well.

 

[tmbrown97]

If they're patch cables and both ends are terminated, it makes absolutely no difference whether they're A or B. That only matters if you're going to cut one end off and punch it down to something. Even if you're planning to cut the end off and punch it down, it's easy enough to work around the difference.

 

[AceCannon]

If they're patch cables and both ends are terminated, it makes absolutely no difference whether they're A or B. That only matters if you're going to cut one end off and punch it down to something. Even if you're planning to cut the end off and punch it down, it's easy enough to work around the difference.

Yeah, I get that, but it isn't clear to me why Elk even recommends to use 568A. In the PDF file for the DBH, the diagram shows the orange and green spliced together (presumably to preserve the rs485 architecture), so it seems to me that either standard works. You should not even have to think about "working around the difference" in this case. Or am I missing something?

(Wiki page showing the difference between 568A and B)

 

[tmbrown97]

Wow... I guess I didn't read the last line of your first post...

I know the whole idea behind using both pairs is that the DBH makes it seem like you daisy-chained everything for the integrity of the RS485 signal - essentially, it sends the signal down one pair and receives it down the other - then sends that one to the next device, etc.

For the work in your closet, since the two pairs are joined anyways at the device, it should make absolutely no difference. The net effect should be identical. And I don't know why they recommend T568A - B is much more common - at least in the PC world.

 

[opie]

Wow... I guess I didn't read the last line of your first post...

I know the whole idea behind using both pairs is that the DBH makes it seem like you daisy-chained everything for the integrity of the RS485 signal - essentially, it sends the signal down one pair and receives it down the other - then sends that one to the next device, etc.

For the work in your closet, since the two pairs are joined anyways at the device, it should make absolutely no difference. The net effect should be identical. And I don't know why they recommend T568A - B is much more common - at least in the PC world.

T568A is much more common in the Home Automation World but I agree in this case it makes no difference as long as both ends are the same.