More Firewire Issues

[Michael Botkin]

This is what I use. One 3 port Firewire card, and one 2 port firewire drive. I have Windows XP, 2gigs of RDRAM, and I use Vegas 4 to edit. It seems that lately I've been having more and more problems with my firewire devices. I have the external HD plugged into the card, as well as my GL2. When I capture footage from the GL2 to the firewire drive, it begins to capture, and then errors out that the drive has been removed. I have also tried plugging the GL2 into the back of the HD instead of my on board card. I get the same errors as well sometimes. Anyone had this problem for have any suggestions?

Michael Botkin

[Rob Lohman]

I'm suspecting a faulty cable or perhaps high levels of interference

[Michael Botkin]

I've tried other cables. When you guys plug your cam in does XP recognize it and pull it up as a small cam icon, then when I turn my drive on, it recognizes that, and then sometimes the cam disappears. Does that help any?

Michael

[Rob Lohman]

Sorry, but I can't help you further then. I'm still waiting on my
own firewire drive to be delivered so perhaps I'll run in to the
same kind of trouble. Also I am on Windows 2000 Professional
and not XP.

[Garret Ambrosio]

Mike,

Remember one thing that is important, the firewire is like a SCSI chain (please note the word like, not saying it is the same but uses a similar principle.) What have we been told ever since grammar school about chains? It is only as strong as the weakest link. Camcorders run using 100 mb/s or S100 most hard drives are configured as S400 or 400mb/s. With the principle of the weakest link in mind, subsequently, the S400 devices will have to be downgraded to S100 when the two devices are sittiing on the same chain. Some devices, like SCSI, do not like to be downgraded and will result in errors.

Try this, borrow or buy a cheap IEEE 1394 card 2 ports will be just fine. Connect your HD on the existing card and connect the cam to the borrowed or cheap port. These two devices are going to be in different IEEE 1394 buses. Now try the capture.

I hope that helps.

[Jeff Donald]

Garret, are you sure about the downgrading? It doesn't work that way on Macs and I would think PC's would have to follow the same FireWire protocols.

[Garret Ambrosio]

I had to review firewire and IEEE 1394 for a case they were working on here at the law firm with Apple and I'm 100% sure that during one of the briefings and white papers it was mentioned that if a S100 device would daisy chain off the S400 the S400 device will downgrade or will be limited to the access of that of S100. So yes, I'm sure.

See what Mike is doing here is, he is creating a chain on the same bus which is probably crippling the heck out of his bus throughput or the HD simply doesn't like to share the connection or the slower connection. It may even be in Windows. Windows may not be utilizing the bus correctly and is causing drops in the the chatter in the bus.

(respectfully) How do you know that your throughput does not degrade on a Mac? IEEE 1394 is the same regardless of OS or Machine, now the way it handles the downgrading may be different. But unless you are seeing the throughput using HDtach or some other device or software (preferrably hardware) there is no way to tell if you are operating at the throughput speeds of S100 or S400.

USB 2.0 on the other hand do not have the limitation of degradation due to different types of USB buses since it utilizes a different topology.


Mike, lastly, the way Firewire or IEEE 1394 is pinned out, it is very easy to short the whole bus, sometimes causing permanent damage to equipment, make sure there is no tension on the wire so that it may cause the plug to move or loosen to cause a short. Oh yeah, make sure you are using an OHCI complaint driver for the firewire card.

[Andre De Clercq]

Jeff, Garet is right, firewire devices with different data rates agree on the highest rate common to both and communicate at that rate, and camcorders mostly have S100
Mike, I suppose your systems are interconnected through 4 wire cables (no supply voltages). Did you try cables (less than 15 feet) with damping ferrites near the ends. Are you using different mains outlets for yr power supply units? Try to use one outlet and try to battery power yr cam (and if possible other parts in the chain) disconnect other devices from yr system (printer,scanner, LAN connection). The reason for all this is because data can be crippled by HFcommon mode currents and standing waves existing on interconnetion cables.

[Jeff Donald]

The 1394 cable standard defines three signaling rates: 98.304, 196.608, and 393.216 Mbps (megabits per second; MBps in this paper refers to megabytes per second.) These rates are rounded to 100, 200, and 400 Mbps, respectively, in this paper and are referred to in the 1394 standard as S100, S200 and S400. Consumer DV gear uses S100 speeds, but most 1394 PC adapter cards support the S200 rate. The signaling rate for the entire bus ordinarily is governed by the slowest active node; however, if a bus master (controller) implements a Topology_Map and a Speed_Map for specific node pairs, the bus can support multiple signaling speeds between individual pairs. The 1394 Trade Association's 1394.1 working group presently are refining and clarifying the setup requirements for handling interconnected devices with multiple signaling speeds.

This is from a 1394 White Paper by Roger Jennings, dated December, 1998.

According to Apple Computer, FireWire supports multiple speeds on the same bus and isochronous data transfer, which guarantees bandwidth for multimedia operations. It has been widely used for attaching digital cameras and other video devices to a computer but has recently begun to see other connectivity applications.

This is from an article on the Oracle Technology Network. My understanding that multiple speed transfer was made possible when the Oxford 911 chip set was implemented in many devices in 2001.

[Rob Lohman]

Very interesting all this. I just bought myself a 160 GB firewire
drive and am wondering whether I get the full potential off it.

As someone else said, without a good hardware metering box
it is not possible to tell the actual speed(s) being used.....

[Jeff Donald]

Rob, even at S100 speeds, Firewire is plenty fast for DV.

Using "isochronous" data transmission, even the S100 implementation supports two simultaneous channels of 30fps (frames per second) broadcast-quality video along with stereo audio.

This from a FAQ at AP Drives.

[Rob Lohman]

I understand... S100 is around 10 MB/s so it can easily hold two
DV streams at 3.6 MB/s. BUT I am more concerned with my
harddisk performance when working with large files. My new
firewire drive has a sustainable transfer rate of 40 MB/s over
firewire (thus supporting the S400 standard). Now if my controller
is running at S200 or everything runs at S100 my harddisk
performance will be severly limited (up to 400%).

The harddisk will not only be used for DV. But also CD and DVD
images (disc images, not pictures) and other large files which
need to be moved to my other IDE drive which also support 40
MB/s (running on an ATA133 controller)....

We'll just have to wait and see

(I will run some benchmarking tests once the device gets here!)

[Akos Szemenyei]

Garett is right to a certain point, you are probably using the same channel on the firewire card and that can definitely cause problems, as far as I know the 3 port firewire cards have 2 channels, try to hook up the drive to the internal port or whichever is the second channel, look in the manual.

As for the firewire chip, it's not exactly the same performance, it totally depends on the manufacturer. Last time I checked the req. for Avid Express DV 3.0 and 3.5, the only the card that was approved had a Texas Instruments chip, other chipmakers were not. So I'm pretty sure that there are quality differences between firewire chips, as between motherboards, RAM etc.

[Andre De Clercq]

Garret, apart fom my earlier remarks, your problem still puzzels me, and after doing some calculations I must conclude that if your cam connection (S100) is active, you will never be able to connect more than one extra DV device because of bandwdth conflicts. So download/upload to yr PC without ext HD and then stop yr cam and do a (highspeed) transfert to the ext HD if needed.

[Michael Botkin]

Didn't mean to start such a debate here! Tell me if this is possible. Lets say I just buy another firewire card, install it in another PCI slot, and plug the drive into that firewire card, and keep the camera and other devices on the first card. Think that will make any difference? My cords are under 15ft and everything works FINE when only one device is plugged in. ONLY when I'm capturing w/ the GL2, and the firewire drive is ON, do I get the problem where one device disconnects.

Michael Botkin