We use the first one (pro connect) for the hub.
We think that this is better than the other two types of hubs that
we've tried, but we cannot say whether this is 'the best'.
Regarding the extension cables, I don't know the manufacturer,
and we were not really suspicious about them as long as we
use only one. The problem occurred when we extended them with
two or more cables; measured voltage drop.
It will be interesting to hear from you whether specific
manufacturer matters for the usb extension cables.
b.t.w, you can try measuring the output voltage at each usb ports;
- one on your pc, end of extension cable, a port on the hub...
bad hub may give too high or too low voltages compared to your pc.
Thanks
- jpaek
Tal Rusak wrote:
I have done some further testing about this issue. Even with USB
extension cables (that otherwise work fine), there are some problems
still. For example, I had one telosb mote that inexplicably stopped
receiving packets from the PC after about 15 minutes in one try,
although it work without failing for over an hour on another trial.
I am wondering which Linksys router you ended up using:
http://www.linksys.com/servlet/Satellite?c=L_Product_C2&childpagename=US%2FLayout&cid=1115416907197&pagename=Linksys%2FCommon%2FVisitorWrapper&lid=0719746152B04
or
http://www.linksys.com/servlet/Satellite?c=L_Product_C2&childpagename=US%2FLayout&cid=1115416907844&pagename=Linksys%2FCommon%2FVisitorWrapper&lid=0784446152B06
Also, did you have success with extension cables from specific
manufacturers?
I appreciate your continued help in advance.
Thanks,
Tal
- Your usb hub is bad? we had to buy three different types of usb
hubs, just to find a good one.
And at least for me, I see more problems when I use an usb hub.
Unfortunately, due to the physical construction of my PC's, I need
to
use some sort of hub or extender to actually connect the motes. I will
try to find another PC where this is not the case. However, I did try
multiple types of extender cables and hubs and the problem seems to
repeat on each of them.
I am not so concerned about the cables as long as you are not connecting
several cables in serial (you can see noticeable power attenuation if
you connect several cables in serial), but the hubs do matter.
Don't trust any cheap hubs. Dlink was not so great. Linksys 4-port was
what we ended up using, but still not as good as no hub at all.
Thank you for your reply.
It appears that several hubs and a certain extension cable were at
the
heart of the problem. With appropriate USB connections, I was able to
get TestSerial working in both directions for up to 1000 packets. I will
do more stress testing with TestSerial and more complex applications in
the next few days.
While the extension cable was probably defective, the hubs appear to
work well with other devices. Do you know why some hubs have such issues
with telosb motes?
Thanks,
Tal
--
Jeongyeup Paek
Ph.D. student
Embedded Networks Laboratory
Department of Computer Science
University of Southern California
http://enl.usc.edu/~jpaek
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