O,T. Connection Firewire

Bobpin wrote on 2/11/2005, 5:59 AM

G'Day all,

How do members connect and disconnect DV camcorders & ADVC 300 to & from the computer.

Do you connect Hot or turn the computer & gear on & off to connect & disconnect.

I ask because I thought Firewire was able to work Hot but I have had my Camcorder & ADVC both go down and lose communication with the computer.




Jimmy_W wrote on 2/11/2005, 6:08 AM
I get the blue screen of death when I unplug hot.
farss wrote on 2/11/2005, 6:11 AM
No problems here. Bear in mind though that 6 pin firewire has a live feed from the PC power supply and it seems is still alive even when the PC is turned 'off'. Treat with care.
4 pin is pretty safe.
Spot|DSE wrote on 2/11/2005, 7:24 AM
I plug hot, but always use the "Safely remove hardware" for disconn. You're just asking for trouble to simply unplug.
Jimmy, you might wanna check the MS 1394 page to see if the new driver patch will fix your BSOD
Jimmy_W wrote on 2/11/2005, 7:26 AM
Thanks Spot!

bumps wrote on 2/11/2005, 7:31 AM
Your problem may be 'static'. Earth yourself out with your camara in your hand, and then you should be able to plug in 'hot'. Peter
Chienworks wrote on 2/11/2005, 7:36 AM
I've never seen a "Safely remove hardware" option for 1394. I only see that come up for USB devices.
GaryKleiner wrote on 2/11/2005, 7:40 AM
I have plugged and unplugged the (hot) firewire connection from DV camcorders and decks approximatly 1.6 million times and never had it cause a problem.

riredale wrote on 2/11/2005, 8:38 AM
Ditto here. I just pull the plug on the camera connection and I get that warm, fuzzy "Beep-boop" sound from my PC, apparently relieved to have one less peripheral device to have to manage.

Where the "Safely remove hardware" becomes important is when you have an external hard drive on the firewire line and the drive has been set up to do write-behind. As I understand it, this is where the drive is smart enough to save up "write to disk" commands for a second or two if there is a great demand for data from the disk. Once the demand has been satisfied, the disk then can take its time writing new data to the platters. But if you suddenly yank out the firewire link, the disk chokes and you get a very ominous "write failure" message. I've trashed a disk this way.

There is an option in XP to cancel the "write-behind" feature for external disks. It that case, you just wait for a quiet moment when there is no disk activity to yank the cord. Really.

Here's another view from a Microsoftie:

"...In a comment, somebody asked what the deal was with the unsafe device removal dialog in Windows 2000 and why it's gone in Windows XP.

I wasn't involved with that dialog, but here's what I remember: The device was indeed removed unsafely. If it was a USB storage device, for example, there may have been unflushed I/O buffers. If it were a printer, there may have been an active print job. The USB stack doesn't know for sure (those are concepts at a higher layer that the stack doesn't know about) - all it knows is that it had an active channel with the device and now the device is gone, so it gets upset and yells at you.

In Windows XP, it still gets upset but it now keeps its mouth shut. You're now on your honor not to rip out your USB drive before waiting two seconds for all I/O to flush, not to unplug your printer while a job is printing, etc. If you do, then your drive gets corrupted / print job is lost / etc. and you're on your own. .."
RBartlett wrote on 2/11/2005, 9:09 AM
Before Gigabit ethernet was commonplace I joined my computers with firewire and on Win2k (that was the thing to have back then) used FireNet to permit networking between them. After using a Belkin firewire hub to join these two PCs wired 6-pin I would from time to time acquire DV footage from my camcorder to just the one PC (with the other PC turned off). Everything was fine with this for more than 24months. I had both PCs and the firewire hub covered by a 600VA UPS (which may have been another flaw in my plan)

Both the firewire cards were cheap cards, one was a TI chipset generic card and the other was a belkin TI card with an extra PSU (molex) feed into it. I had two other devices I'd connect to the firewire hub, a Maxtor OneTouch 7200 rpm drive and a generic compact-flash firewire reader (for a microdrive MJPEG capable stills camera made by Sanyo).

Well, on this one occasion I plugged my Maxtor 120GB drive in "hot" and nothing happened. Note this was a PSU powered HD and I was using a 6-pin to 4 and 4-to-6 interconnect cable unlike my normal 6-to-6 cable. So I wondered what was going on and with it being a maxtor just figured it must have died from shoddy build quality. So I didn't consider a fault having occured on the Belkin firewire hub and proceeded to plug my Sony camcorder in (which is of course 4-pin only on the device itself).

No more Hard Disc and no more firewire on the camcorder. Fortunately this was a US$1000 camcorder that I'd worked since 1999 and that I could replace with a similar quality for US$350. Indeed otherwise it was working so I could use to to capture and even SVIDEO/comp-video out.

I did some research as to what sort of ground loop protection and power isolation existed in the firewire specification. Well, what I suspect I have lost is the signal diodes on one or more of the 4 pins of my HD and Camcorder.

What Tyco/Raychem have to say on the subject deserves some reading. Whilst they are talking about 6 pin mode protections in the design guides I have read. The use of PolySwitch protection circuits appears to be the path ahead for Firewire. Otherwise there is always a risk that the 0V/Gnd of these SELV circuits could be at a very different electrical potential to either end. Something then has to take on this surge current or actually breakdown. The polyswitch is a self resetting fuse. Protects but doesn't destroy itself and is suitable for these sub 30V 45W supporting circuits.

Nobody appears to use polyswitches in the firewire computer ports, hubs or external drives. Can't say what is in my old Sony camcorder, but it appears to be not enough as the port died.

So my conclusion is that firewire isn't particularly fantastic. The software/driver models and CPU utilisations seem to be lower for firewire than USB/USB2. However I actually think everything may aswell have a Gigabit ethernet port with optional Power over Ethernet support. PoE is a large DC voltage but it is requested before the injection begins. So if you don't need it you don't get it. Whatever the wiring is going to do.

Would I plug the kit in hot for firewire? Well, yes I probably would if I hadn't had this experience. It is designed to do this. However it isn't designed to handle fault conditions very well. So either ensure you have great insurance for accidental damage within your age of stock. Or start suggesting that everything gets GigabitEthernet instead of USB2 and Firewire800 on it. About the only thing nicer than 1000Base-T GigEth is SDI/ASI. However I would wager that it would be cheaper to give a camera a GigEth port than anything else. Also that if everything is going towards solid state and tapeless magnetic recording, then why not use what computers like most. Ethernet and web/SAN technology. No more need to settle on FAT-32 as the disc format either.

Sorry for the rant. I just think that we don't need quite so many different types of interfaces doing the same job with some having poor ergonomic characteristics. Even I can make a good GigEthernet compatible patch cable but I have to pay someone for a firewire interconnect. rant rant rant
Spot|DSE wrote on 2/11/2005, 9:53 AM
You must not use Firewire hard drive tanks?
It's dangerous to disconnect a hot firewire plug for 2 reasons;
1. the i/o buffer may still be active/unrefreshed.
2. If the devices are communicating, you CAN send an all-off message to your other firewire devices. If you're using drives in conjuncition with the cam as many people do, you could corrupt the data or if the drive is powered via 6 pin, you could damage the drive's power buffer. (not likely, but the boyz at ADS say it happens somewhat regularly)

B.Verlik wrote on 2/11/2005, 10:21 AM
Also. Be sure to wear your reading glasses when you plug in a 1394. I know from experience, that the plug will easily go in up-side down. I lost one of my 1394 connectors on my A/D converter due to that. (Luckily, I had two.)
RBartlett wrote on 2/11/2005, 10:27 AM
Perhaps you didn't mean me Spot, but I hadn't myself used the Maxtor drive at the same time as my camcorder. The purpose of the belkin hub had been in the pursuit of isolating the power lines from the two PCs and it was convenient to not be ferreting behind the PC for a socket. However I wish I had now. I made the mistake of thinking that I had an idiot proof setup and was not really pushing the envelope but was rather being precautious.

Incidentally, if you shouldn't unplug hot because of the power buffer risk, there is therefore some risk in non-simultaneous energising of firewire equipment too. So there is a risk if we don't plug everything cold and then power it all on together from the same wall switch/isolator? Then what about the delay to press the PC power on switch or the UPS or.....

Just stikes home to me that Firewire, the electrical implementation that we see when we buy it, isn't upto rigorous use. Whereas, gigethernet and power-over-ethernet probably is exactly what we want. The concern that Ethernet has a tendency to not care too much for isochronous transfers is somewhat moot when you plug it in a point-to-point (non-shared, non-switched) topology. However I was burned, so I'm a little biased. Like you said, firewire similarly doesn't lend itself to every type of peripheral daisy chained on the same PHY interface.

If I've got something expensive then I now treat both USB and firewire as if it were a parallel port connection. I know this is paranoid but my pockets aren't deep and I don't have insurance for my older kit. I'd advise similarly to others who can't afford a failure and don't have a friendly service center nearby.

I believe there are now some US$50 isolators that should provide "aftermarket" polyswitch protection on power and data lines. However I can't quite bring myself to buy or recommend them. SDI and analogue component interconnects don't have any of this to consider either do they?
Bobpin wrote on 2/11/2005, 7:25 PM

Thanks for all your replies

I don't get a blue screen,I just don't get the Beeps.

I can't see anywhere to "safely unplug", as I do with USB

Actually I hot plug my Sony dcr trv9 cam & have never had a problem it was my PD 170 & ADVC 300 that are in for repair,maybe
the older cammera is made of better stuff. LOL

I will go with you more experienced people and hot plug as needed

Thanks again