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Guest Message by DevFuse

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Max external hard drive size


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22 replies to this topic

#1 OFFLINE   girdnerg

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Posted 06 November 2013 - 10:17 AM

Been a while since I checked. Is the Max EHD size still 2TB? Does the enclosure still have to be USB 2.0 only?

 

This is for my current 722k.

 

Thanks



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#2 OFFLINE   thomasjk

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Posted 06 November 2013 - 10:49 AM

Yes to the 2TB. I can't answer about the enclosure but I'd assume USB 2.0.



#3 OFFLINE   girdnerg

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Posted 06 November 2013 - 11:06 AM

I looked up on the Dish website. It did say 2TB was the limit, but it only stated that it must support USB 2.0.

 

Do you folks think one of the new USB 3.0/2.0 would work, or does it has to be USB 2.0 only?

 

thanks



#4 OFFLINE   P Smith

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Posted 06 November 2013 - 03:33 PM

will works fine: by USB standards USB 3.0 enclosure's controller will negotiate down to 2.0 if a host [DVR] will not accept 3.0 state

 

as to using 3.0 TB drive ... try to search, I recall I did try it last year or two



#5 OFFLINE   girdnerg

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Posted 06 November 2013 - 03:59 PM

Thank you both for the answers. I knew it had to be USB 2.0, but didn't know if a 3.0 would negotiate down to 2.0 of the 722k DVR.


Edited by girdnerg, 06 November 2013 - 04:20 PM.


#6 OFFLINE   beetle02

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Posted 22 January 2014 - 01:32 PM

Does the hard drive have to be powered?


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#7 OFFLINE   thomasjk

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Posted 22 January 2014 - 02:07 PM

According to Dish yes. Some folks have reported running EHDs powered from the USB port.



#8 OFFLINE   P Smith

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Posted 22 January 2014 - 02:17 PM

usual max current off US port is 500 mA

 

so check your drive first, no more 0.5 A


Edited by P Smith, 22 January 2014 - 02:18 PM.


#9 OFFLINE   wje

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Posted 24 January 2014 - 05:13 PM

Two things to keep in mind:

 

While the running current for a drive can be well under 0.5A for notebook-style drives, the STARTING current is significantly higher. Most consumer sites don't list spin-up power. a "2 watt" drive is 2 watts running. Example: A WD 1TB 'green' laptop drive has a running (and not seeking) consumption of about 340 ma, its peak spinup draw is close to 1 amp. Check the real mfgr's data sheet.

 

Second, although the USB spec does call for providing 500ma, there's no reason to expect Dish to meet that. They might, they might not. They aren't providing a port to connect any random USB widget, it's purpose-added to allow writing to/from an external drive for a specific purpose.


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#10 OFFLINE   P Smith

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Posted 24 January 2014 - 05:22 PM

if they print the USB logo, then it is certified to provide 500 mA by specs



#11 OFFLINE   wje

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Posted 24 January 2014 - 09:50 PM

Correct, but that's not on my 722K. Note that the old universal symbol for USB (the black squiggly lines with the dots on the ends) is NOT a certified mark. Refer to USB.org


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#12 OFFLINE   P Smith

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Posted 24 January 2014 - 10:42 PM

put slightly different logo to avoid pay license fee to USB org and same time do not fulfill one  major parameter of all USB ports: max load [500 mA],  would be disaster for the mfg; ppl will not do detective work on the logo and will connect USB devices to the ports. Perhaps you know list of supported devices by e* DVRs: cameras, keyboards, mice, Ethernet adapters, etc


Edited by P Smith, 24 January 2014 - 10:43 PM.


#13 OFFLINE   wje

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Posted 25 January 2014 - 12:28 PM

I don't know why I persist with these silly arguments, but in order to provide some actual information, I did what any real engineer would do... I measured what the 722K port can actually provide. I used a programmable current sink (being an engineer at a very large electronics company has a few benefits) and measured the USB voltage under various loads.

 

The port not only can't source 0.5A, it doesn't even come close. About 100 ma is it. At 200 ma, the voltage drops below 4.4V, which is the rock-bottom voltage you could hope to run a 5V device from, and nothing near what you need to spin up any drive I've come across.

 

Moral: believe what Dish says... use an external power supply.


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#14 OFFLINE   P Smith

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Posted 25 January 2014 - 12:36 PM

well, I see we got someone who could do that properly :) I never had time to test all the DVR what I used, starting from 501, ending 813 ... [did you use Kikusui PLZ eload device ?]



#15 OFFLINE   wje

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Posted 25 January 2014 - 12:57 PM

Kiethley 2400, a bit of overkill.


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#16 OFFLINE   P Smith

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Posted 25 January 2014 - 01:00 PM

sure ... definitely not for home/garage lab



#17 OFFLINE   wje

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Posted 25 January 2014 - 02:43 PM

To beat this completely to death, allow me to present my long-winded rationale why the port is so anemic. Slightly off topic, moderator please forgive me, but I'm watching STTNG: Nemesis for the Nth time. My sincere apologies to real Dish employees, unless of course the shoe fits. And I expect all the engineers will think it does. At least, the competent ones. The incompetent ones will become UEMs.

 

Idiot Marketing Guy (IMG): We need something to differentiate us from the competition. How about "You can save a zillion years of programming on our DVR!".

 

Useless Engineering Manager (UEM): Hey, Underpaid, Overworked Engineers (UOE)s, Make It So. Work smarter, not harder. Socialize the design. Empower the group!

 

UOE: Sure, we can just add a 4 TB drive, no problem. It will only add $500 to the cost. (Apply the steep cost increase with capacity at the time the design was being done).

 

Really Shoud Die Bean Counter (that gets paid far more money than he saves) (RSDBC): You're out of your minds. My spreadsheet clearly shows that we can't recover this cost this month. Unacceptable. The fact that we'd triple our customer base is totally irrelevant because my bonus is determined by how many pennies I can save this quarter even if we lose huge amounts of money later.

 

UOE: Ok, well, the chip we use does have a USB interface. It's supposed to have a USB driver chip on it, but we could expose it and require the user to provide their own drive. It can't support normal USB power, though, so they'd have to have an external power supply, too. We'll only have to add 12 cents in parts cost. (Ignoring the Very Underpaid and Very Overworked Software Engineers, 'cause, really, how hard can it be? It's just some code. Suck it up.)

 

RSDBC: Marginally acceptable. I can move this column to that column, cut some employee benefits, and my bonus will be fine. Ok, do it.

 

IMG: Even better! We can pitch this as giving the user complete freedom to back up anything they want, and to add Their Very Own Disk, not something owned by us! Fabulous!

 

UEM: Make It So! Remember to socialize it. Run a flag up the flagpole. Don't forget a Straw Man. Throw it on the wall and see if it sticks. Don't drop the ball.

 

UOE: I hate all of you. I need a new job.

 

This is my life.


Edited by wje, 25 January 2014 - 02:53 PM.

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#18 OFFLINE   P Smith

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Posted 25 January 2014 - 04:02 PM

Man ! I would add some ... but for now, I would just agree with all that you said above !

 

[that would be USB ORG certification... FCC, UL, etc]



#19 OFFLINE   Stewart Vernon

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Posted 25 January 2014 - 09:39 PM

All I will add is... I worked for a company that did this sort of thing.  There were computers that supported USB for keyboard and mouse but not a lot else.  Tech Support wanted support for USB thumb drives but had to fight an uphill battle.  The designers basically wanted to put a USB port on the board and only test it for keyboard and mouse input... nothing else... and invariably nothing else would work as a result.  I'm pretty sure it generated customer complaints from people that expected a USB port to support USB devices.


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#20 OFFLINE   P Smith

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Posted 26 January 2014 - 12:24 AM

Stuart, then the computer/board would not be USB org certified ! And your company had no right to put official USB logo on it.Or claim it as standard USB port.






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