USB problems

[malc-c]

OK this one has me stumped. It's all pointing to a clash between the USB ports on an old HP computer and a USB active cable, but I don't know why or what to change (other than run another cable) to resolve this.

I have an active USB cable (5m) running from the PC to a powered D-Link 7 port hub, into which I have an EQDIR cable, HitechAstro USB focuser, and a NexImage web cam.

Everything works well apart from capturing from the webcam via Sharpcap. To work out what may be the cause here is what I've tried.

1) - plug the NexImage direct into the USB port on the PC - works OK

2) - plug in a Phillips 880 (flashed to 900) webcam in the hub - same interference

3) - plug the same camera into the PC and works fine

4) - plug either camera into the hub and plug the active cable into my netbook - work fine - NO interference

5) - Tried all 6 USB ports on the HP PC with the active cable - interference

6) - Connect the web cam to the active cable - interference

The interference is as if a switching is happening (polling) -

Here is the cable I'm using

The reason I'm using an active cable is because when I used a standard 5m USB cable with my Canon dSLR the data was often lost. I've yet to try my 400D with the active cable (can't find my serial shutter release !)

Ideas - suggestions. I don't want to purchase another active cable only to find out that it does exactly the same, afterall it works fine with my little Asus 900A netbook !!

[martin_h]

Is the HP using USB 1 or 2 ? If the HP is very old it might only have the older(slower) USB ports, and therefore can't cope.

[malc-c]

Thanks for the reply,

Whilst they are a few years old they appear to have USB 2 ports - Here's the spec, and as mentioned, when connected direct the cameras work.... it's just when I use the active cable that I have the problem.

At A Glance

• AMD Athlon™ 64 and Sempron™ processors with HyperTransport™ technology
  
• Operating Systems:
  Genuine Windows XP Professional SP2
  Genuine Windows Home Edition SP2
  Genuine Windows XP Professional x64 Edition
  SuSE Linux 9.3
  FreeDOS
  
• Support for AMD Enhanced Virus Protection™ and AMD Cool 'n Quiet™ technologies
  
• Integrated DDR I dual-channel memory controller
  
• ATI Radeon® Xpress 200M chipset
  
• Integrated Radeon X300 based graphics – standard VGA and DVI-D ports
  
• Supports up to 4-GB of PC 3200 (DDR 400) Synch DRAM Memory
  
• 6 rear USB 2.0 ports and 2 front USB 2.0 ports
  
• Realtek AC97 integrated audio with internal speaker
  
• Integrated PCI-E Broadcom NetXtreme Gigabit Ethernet NIC
  
• x1 and x16 PCI-Express slots
  
• Two 32-bit PCI slots
  

I'll try and see if a standard 5m passive ext cable works... it may be that the ports on the HP are powerful enough that the signals won't be lost.

Do USB ports have timing issues - it's as if it's loosing it's framing signals causing thick bars to appear in pulses (can't capture it as the PC isn't yet on the network). Oh and I've installed windows 7 on it which is running quite sweetly

[ScubaMike]

If the PC is more than 3-4 years old, it may be that the front ports are indeed V1.1

Have you tried other ports? (the ones at the back tend to be USB2 when there is a mix on a system).

[malc-c]

Yup, tried all ports front and back

[Merlin66]

I ended up using a LINDY active cable to my powered 6 port USB hub.

Touch wood everything had been working great (as long as you mark each port with the name of the camera and ONLY plug it into that port!!)

[Merlin66]

What else are you running from the USB hub?

Any other cameras?

[malc-c]

I'm hoping to try an experiment later... I have 3 x 2m USB ext leads, so I'll try daisy-chaining them together and see if that works. If so then I'll ditch the active cable and run in a new 5m passive cable in its place

[Earl]

If I can suggest, it might be worthwhile using a dedicated port on the computer for the camera and not putting it through the hub.

I had loads of usb issues so i just ended up making a small itx pc and having it next to the scope, I then have a 10m vga and 2 active usb leads for keyboard and mouse.

Im going to move over to a HDMI lead for video next as it has far better quality over the lenght.

[malc-c]

Thanks for the suggestions..

Been doing some experimenting and it appears that the problem only occurs when using a camera connected to the D-link hub. I replaced the active cable with a 3m USB passive cable straight into the hub and got the same interference when either web cam was connected. Made up a long passive cable using male-female ext cables and connected the camera direct to the PC and it works fine

The only thing I cant work out is why the interference doesn't happen when using the active cable and hub with the netbook

[malc-c]

Ok, spent a few hours making up new cables and running them in between the warm room and scope. The Hub is used for control via EQMOD so has my home made EQDIR cable, and has the AstoTech usb focuser connected. I've run separate USB cables for the NexImage and Canon camera, and managed to install the serial shutter release for the camera too. I'm pleased to say that this arrangement now works fine.

I'll guess I'll never get to the bottom of what was causing the issue with the hub and webcams...

[Earl]

Ok, spent a few hours making up new cables and running them in between the warm room and scope. The Hub is used for control via EQMOD so has my home made EQDIR cable, and has the AstoTech usb focuser connected. I've run separate USB cables for the NexImage and Canon camera, and managed to install the serial shutter release for the camera too. I'm pleased to say that this arrangement now works fine.

I'll guess I'll never get to the bottom of what was causing the issue with the hub and webcams...

I think with USB its a play till it works... today maybe not tomorrow though LOL