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#16
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USB Cable too long?
On 30/08/2018 16:02, Mayayana wrote:
"Fokke Nauta" wrote | If the scanner is the problem, that it can't handle the length of the | USB cables, it would be a problem with my pc as well. Not necessarily, if it's just near the max length that the scanner can handle. But it's just one idea to rule out. | Motherboard perhaps? Too old? USB 2.0 inputs, whereas my pc has USB 3.0 | inputs. | Should this make the difference? | I've never seen problems with different machines, except that sometimes they seem to require using them in order. That is, #3 port may seem dead if there's nothing plugged into #2 port. I tried several USB ports. Didn't make a difference. As Al said, it works when you plug it in direct. Correct So doesn't that only leave the switch, a cord, or cord length as variables? Maybe try switching the switch connections? I did. Changed the cables as well. No difference. I've never used a USB switch, so I don't know about that, but I wonder if there could be some kind of priority glitch. For instance, your PC turned on and somehow getting "first dibs" on the connection. I guess you could test that by turning off your PC and/or unplugging your PC but still leaving the other hooked up via the switch. It's just an ordinary switch, which connects one cable or the other. What I'm doing is first setting the switch to the desired pc, and then turn the scanner on. PC's are always on (Not at night). Both pc's, on their turn, see that the scanner is on and recognize it. But only on my pc I am able to scan. Fokke |
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#17
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USB Cable too long?
On 30/08/2018 15:35, Big Al wrote:
On 08/30/2018 09:26 AM, Fokke Nauta wrote: On 30/08/2018 15:14, Mayayana wrote: "Fokke Nauta" wrote | Could it be that total cable length is too much? | Why is the scanner then working allright with my pc? I wouldn't dismiss the other two answers, but I have found that hardware varies. And some devices will tell you in their manuals what the length of a cable can be. We have a high-end Epson photo printer and a budget, everyday printer. (I think the latter may be HP.) Only one can fit near the computer, so there's a 12' USB cord for the other. The Epson simply won't tolerate that cord. The everyday printer doesn't mind at all. So it could be the ports, the switch, the systems.... But it's also possible that you've set it up at the high end of the cable length it will tolerate. On the bright side, all of the ideas presented so far are easy to test. If the scanner is the problem, that it can't handle the length of the USB cables, it would be a problem with my pc as well. Same type of cables, same length. But my system works well with the scanner. Tried different USB inputs on my wwife's pc. Didn't make a difference. Motherboard perhaps? Too old? USB 2.0 inputs, whereas my pc has USB 3.0 inputs. Should this make the difference? Fokke But you say your wife's pc works if hooked straight in. So the port is okay. The only variable in this argument is the switch and your wife's USB port not compatible. I can't believe the switch only works on USB 3 but that could be an idea if you have docs on it. But most USB3 are backwards compatible. Real head scratcher. Yes, it is. It's an USB 2.0 switch. To my opinion just an ordinary switch. Fokke |
#18
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USB Cable too long?
On Thu, 30 Aug 2018 19:55:11 +0200, Fokke Nauta
wrote: To my knowledge an USB hub is to connect multiple USB devices to one pc. Yes. What I'm doing, is to connect one USB-device with two pc's. Not simultaneously, but either one or the other. One can't use a hub for that. Have you tried using a hub for that, reversing its connections? I'm not saying that it will work, since I don't know and I also doubt it, but it might be worth a try. Let me ask why you want to do that. I sometimes move a thumb drive from a USB port of my computer to one on my wife's. It's easy enough to do that, so I've never the need for something like what you're talking about. |
#19
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USB Cable too long?
On 30/08/2018 20:32, Ken Blake wrote:
On Thu, 30 Aug 2018 19:55:11 +0200, Fokke Nauta wrote: To my knowledge an USB hub is to connect multiple USB devices to one pc. Yes. What I'm doing, is to connect one USB-device with two pc's. Not simultaneously, but either one or the other. One can't use a hub for that. Have you tried using a hub for that, reversing its connections? I'm not saying that it will work, since I don't know and I also doubt it, but it might be worth a try. No. How about the connecors, which need to be reversed as well? Let me ask why you want to do that. I sometimes move a thumb drive from a USB port of my computer to one on my wife's. It's easy enough to do that, so I've never the need for something like what you're talking about. We have one scanner and two pc's. We both want to use the scanner. Fokke |
#20
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USB Cable too long?
Fokke Nauta wrote:
On 30/08/2018 16:08, Paul in Houston TX wrote: Fokke Nauta wrote: Hi all, We have an Epson flatbed scanner, V600 Photo. It is connected to an USB switch by a cable of 1 meter. One output of the switch is connected with my pc by a cable of 1.8 meter. Scanner works fine. The other output of the switch is connected to the pc of my wife (W7 Pro 64b, mobo: ASUS P7P55D). This cable is also 1.8 meter. On this pc the scanner is recognized, the system bleeps when the scanner is turned on. Scanning is impossible, it gets stuck, the led on the scanner keeps flashing, and nothing further happens. Doesn't make a difference when I use Photoshop or the Epson utility for scanning. When I connect the scanner straight away to my wife's pc with a cable of 1 meter, it works fine. I use Belkin USB cables, thought they are good quality. The USB switch is König, passsive. Could it be that total cable length is too much? Why is the scanner then working allright with my pc? What type of cable should I order to make sure the scanner works allright with my wife's pc? Fokke It's possible that the scanner is not compatible with the unknown model of König usb hub. From the König website: "This switch is not compatible with devices that requires a constant connection to a computer. Usually these are devices like multifunctionals or laser printers." You might be right. But then again, why does it work on my pc and not on my wife's pc? And isn't a USB not just an ordinary switch, which connects one wire or the other? Should be fine, shoudn't it? Fokke Don't know why it works on one machine and not the other. Putting "usb hub insides" into google images shows they have quite a bit of circuitry inside. |
#21
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USB Cable too long?
On 30/08/2018 21:57, Paul in Houston TX wrote:
Fokke Nauta wrote: On 30/08/2018 16:08, Paul in Houston TX wrote: Fokke Nauta wrote: Hi all, We have an Epson flatbed scanner, V600 Photo. It is connected to an USB switch by a cable of 1 meter. One output of the switch is connected with my pc by a cable of 1.8 meter. Scanner works fine. The other output of the switch is connected to the pc of my wife (W7 Pro 64b, mobo: ASUS P7P55D). This cable is also 1.8 meter. On this pc the scanner is recognized, the system bleeps when the scanner is turned on. Scanning is impossible, it gets stuck, the led on the scanner keeps flashing, and nothing further happens. Doesn't make a difference when I use Photoshop or the Epson utility for scanning. When I connect the scanner straight away to my wife's pc with a cable of 1 meter, it works fine. I use Belkin USB cables, thought they are good quality. The USB switch is König, passsive. Could it be that total cable length is too much? Why is the scanner then working allright with my pc? What type of cable should I order to make sure the scanner works allright with my wife's pc? Fokke It's possible that the scanner is not compatible with the unknown model of König usb hub. From the König website: "This switch is not compatible with devices that requires a constant connection to a computer. Usually these are devices like multifunctionals or laser printers." You might be right. But then again, why does it work on my pc and not on my wife's pc? And isn't a USB not just an ordinary switch, which connects one wire or the other? Should be fine, shoudn't it? Fokke Don't know why it works on one machine and not the other. I haven't got a clue either... Putting "usb hub insides" into google images shows they have quite a bit of circuitry inside. Yes, USB hubs do. But my USB switch is a simple switch. Connecting one wire to the input connector or the other wire. Fokke |
#22
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USB Cable too long?
On 8/30/2018 8:00 AM, Fokke Nauta wrote:
Hi all, We have an Epson flatbed scanner, V600 Photo. It is connected to an USB switch by a cable of 1 meter. One output of the switch is connected with my pc by a cable of 1.8 meter. Scanner works fine. The other output of the switch is connected to the pc of my wife (W7 Pro 64b, mobo: ASUS P7P55D). This cable is also 1.8 meter. On this pc the scanner is recognized, the system bleeps when the scanner is turned on. Scanning is impossible, it gets stuck, the led on the scanner keeps flashing, and nothing further happens. Doesn't make a difference when I use Photoshop or the Epson utility for scanning. When I connect the scanner straight away to my wife's pc with a cable of 1 meter, it works fine. I use Belkin USB cables, thought they are good quality. The USB switch is König, passsive. Could it be that total cable length is too much? Why is the scanner then working allright with my pc? What type of cable should I order to make sure the scanner works allright with my wife's pc? Fokke Exchange PC connections on switch and observe if that exchanges which PC works. -- Zaidy036 |
#23
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USB Cable too long?
On 8/30/2018 8:00 AM, Fokke Nauta wrote:
Hi all, We have an Epson flatbed scanner, V600 Photo. It is connected to an USB switch by a cable of 1 meter. One output of the switch is connected with my pc by a cable of 1.8 meter. Scanner works fine. The other output of the switch is connected to the pc of my wife (W7 Pro 64b, mobo: ASUS P7P55D). This cable is also 1.8 meter. On this pc the scanner is recognized, the system bleeps when the scanner is turned on. Scanning is impossible, it gets stuck, the led on the scanner keeps flashing, and nothing further happens. Doesn't make a difference when I use Photoshop or the Epson utility for scanning. When I connect the scanner straight away to my wife's pc with a cable of 1 meter, it works fine. I use Belkin USB cables, thought they are good quality. The USB switch is König, passsive. Could it be that total cable length is too much? Why is the scanner then working allright with my pc? What type of cable should I order to make sure the scanner works allright with my wife's pc? Fokke -- Zaidy036 |
#24
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USB Cable too long?
Ken Blake wrote:
On Thu, 30 Aug 2018 19:55:11 +0200, Fokke Nauta wrote: To my knowledge an USB hub is to connect multiple USB devices to one pc. Yes. What I'm doing, is to connect one USB-device with two pc's. Not simultaneously, but either one or the other. One can't use a hub for that. Have you tried using a hub for that, reversing its connections? I'm not saying that it will work, since I don't know and I also doubt it, but it might be worth a try. Let me ask why you want to do that. I sometimes move a thumb drive from a USB port of my computer to one on my wife's. It's easy enough to do that, so I've never the need for something like what you're talking about. A "hub" has active regeneration in the path. The upstream is the host, the downstream is the peripheral. Upstream | | packet regeneration | | | | Down Down Down Down Stream Stream Stream Stream A "mechanical switch", doesn't need anything. This could also be implemented with QuickSwitches or transmission gates or something similar. The total cable on either side ("path length") cannot exceed 15 feet. If you put 15 feet of cable on upstream, 15 feet on downstream, that's 30 feet total and too long. Only if the switch happened to have digital regeneration (effectively, be a switch with a 1-port hub built into each path), could you support 15 foot cables on either side. I've not seen a photo of what's in these things, to know, but the price suggests a cheesy mechanical switch. Upstream1 Upstream2 | | | | D+ D- D+ D- | | | | \ \ / / \ \ / / Mech Switch A-B | | D+ D- Downstream | | To USB Printer That's my interpretation, and the above assumes USB2. I don't know how or if, all the same solutions exist for USB3. USB3 has TX+ TX- GND RX+ RX- === 5GHz interface USB3 rate +5V D+ D- GND === 480Mbit/sec USB2 interface and the 5GHz part is similar in design to PCI Express or SATA differential signaling. The USB2 four pin interface is not nearly the same quality. In its lowest speed modes, it runs single-ended and the wiring is also half-duplex, which doesn't help matters. The nice thing about USB3, is it's full duplex, you can TX and RX at the same time, and the role and function of each pin is more fixed (the RX pair can have a 100 ohm resistor permanently affixed as flyby termination, that sort of idea). Paul |
#25
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USB Cable too long?
Fokke Nauta wrote:
We have an Epson flatbed scanner, V600 Photo. It is connected to an USB switch by a cable of 1 meter. One output of the switch is connected with my pc by a cable of 1.8 meter. Scanner works fine. The other output of the switch is connected to the pc of my wife (W7 Pro 64b, mobo: ASUS P7P55D). This cable is also 1.8 meter. On this pc the scanner is recognized, the system bleeps when the scanner is turned on. Scanning is impossible, it gets stuck, the led on the scanner keeps flashing, and nothing further happens. Doesn't make a difference when I use Photoshop or the Epson utility for scanning. When I connect the scanner straight away to my wife's pc with a cable of 1 meter, it works fine. I use Belkin USB cables, thought they are good quality. The USB switch is König, passsive. Could it be that total cable length is too much? Why is the scanner then working allright with my pc? What type of cable should I order to make sure the scanner works allright with my wife's pc? Is it actually a USB switch or is it a USB hub? Are there switches (mechanical or software-controlled) as to which ONE output of the USB switch will currently be connected to the USB port on the PC to which that USB switch is connected? That is, can only one USB device be used at a time with the USB "switch"? If only one USB device on the output side of the USB switch can be used at a time then it is a switch. There would be some means of selection which output port got connected to the input port of the switch, and the other output ports are disconnected. If all USB devices are [expected to be] concurrently accessible that are connected to the output of the "switch" then it really is a USB hub. Is it really a hub and there are multiple switches on it to simply disable/unpower the individual output ports? Got a model of the USB switch? You mentioned "Konig" but they've had several different models of USB switches some of which are discontinued. At Konig's site, the only one that I found they currently produce is: https://www.konigelectronic.com/comp...h-black-795543 which warns: This switch is not compatible with devices that requires a constant connection to a computer. Usually these are devices like multifunctionals or laser printers. That is used to share a USB device (printer, scanner, etc) to 2 computers. That is, its input port goes to the USB device and its output ports go to the USB ports on 2 different computers. That way, when you press the toggle button, the one USB device gets toggled between the two computers' USB ports. That USB switch itself requires no drivers. It merely mechanical (well, electronically) performs a change in pathing between the one input port from the USB device to the two output ports to the computers. I'm not sure the switchover of the 5V power (coming from the PC's USB port) would be smooth. Which PC's USB port would be supplying the 5V power during a switch? Does it have some electronics to smooth out the power switch when changing which PC to which the USB device is connected (which means it would need a capacitor to maintain power during the glitch at the time of the switch). That momentary loss of 5V power during the switch could force the USB device to initialize again. The Epson V600 scanner has its own A/C power supply, so it doesn't need and probably doesn't use the 5V from the USB connection. However, it's possible the USB 5V power is used when the USB device goes into sleep mode (to power the sensing logic in the USB device to know when it should wake up). The total length of the USB connection would be from the USB device's USB port through the length of USB cable connected to it to the USB switch, the pathing internal to the USB switch, and then the length of USB cable from the USB switch to whichever PC the switch was currently configured to connect. USB device (scanner) - 1 meter USB cable - USB switch - 1.8 meter USB cable - computer's USB port. That's just a tiny bit over 2.8 meters. The maximum length for a USB2 cable is 5 meters for full-speed USB devices, 3 meters for low-speed USB devices. To go further means you need to insert an active USB extender aka repeater (amplifies and cleans up the signal and ensures 5V gets to the USB device - cheap ones don't do the latter, they may recondition the signal but pass on the power as-is). USB 3 has a max length of 3 meters. According the Konig's specs, their 2-port USB switch only handles USB 2. There is also the issue with handshake timing; see: https://superuser.com/a/1105099 If the switch between computer's for the 5V power isn't smooth or the switch provides its own power to the USB device, a glitch could result in the device reinitializing which will be a hell of lot longer than the link failure timeout. The Konig switch has no A/C power adapter, so it must switch the 5V power from the USB cable to one computer to the 5V power from the USB cable to the other cable but without dropping the power. I don't know what your USB device(s) has(have) to cover very short power glitches (outages). Konig's specs are minimal, so no information on how they smooth the 5V power switchover. Their "support" page, after entering "CMP-USBSW2" and selecting their USB switch, just dumps me back to their product page which tells me nothing about HOW that switch operates. Back in the mechanical switch era, you needed a make-before-break switch to ensure no disruption in power. All they note is the statement that I commented under the link above for their product page. Besides the issue of switching the power to the device from the two computers, how about USB enumeration? When you toggle, the same device will now appear as a new connect to the computer to which you toggled. Handshaking takes some time and there isn't an instantaneous bong-bing tone notifying you the device has sent its presentation data and becomes recognized. That's probably why Konig mentions their switch won't work with devices that require a constant connection (once connected). Those devices don't tolerate disconnects without having to reinitialize again. They dis-recommend you using their USB switch with multifunctional (MFC) and laser printers. Is a scanner that different, especially if it expects to use 2-way communication to report status of the device? They provide a passive USB switch. I've seen powered USB switches that claim "Stable connection: USB 2.0 sharing switch with a separate micro female port for optional power, optimizing its compatibility with more devices, such as ...", noted at: https://www.amazon.com/UGREEN-Select.../dp/B01MXXQKGM (but you have to provide the power adapter that has a micro USB connector) By providing their own power to the USB device(s), they don't encounter glitches in the source USB's 5V power during the switch. That one happens to be a USB3-capable switch. Have you tried powering down the scanner BEFORE using the USB switch to toggle between PCs. PCs are up, power down the scanner, press the toggle button on the USB switch, power up the scanner. Else, it looks like you need to use a powered USB switch (not USB powered but line powered). Alternatively, add a powered USB hub between the USB switch and the USB device (scanner). I've seen those sell new for under $10 but that's on the low-end, like: https://www.newegg.com/Product/Produ...9SIA6SY2B99168 No spec on the adapter to know how much load it can handle across all 7 ports, and it's too small to handle a full load on all of them. https://www.newegg.com/Product/Produ...82E16817111402 They give a 3A rating for their power adapter to spread across all USB device ports. https://www.newegg.com/Product/Produ...82E16817182057 Although the same price as the Dlink, their adapter puts out only 2A. I think I've seen powered USB hubs that had a 48W power converter (probably for 4-port USB3 powered hub with a 2.4A charging port) but that's a large brick sitting in the middle of the cord, not a walwart hanging from an outlet. |
#26
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USB Cable too long?
On 08/30/2018 11:36 AM, NotMe wrote:
USB 3 puts out more power than USB 2, get a powered USB hub. I suppose you know it doesn't actually put out more power unless the connected device requests more power. In the same way, a 100mA nightlight plugged into a 20A household circuit will draw 100mA, not 20A. Also, those numbers (500mA for USB2, 900mA for USB3) are MINIMUMS. As to maximums, I've heard the connectors can handle 5A. I've known USB2 ports that can supply more than 2A. |
#27
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USB Cable too long?
On 08/30/2018 12:55 PM, Fokke Nauta wrote:
[snip] To my knowledge an USB hub is to connect multiple USB devices to one pc. What I'm doing, is to connect one USB-device with two pc's. Not simultaneously, but either one or the other. One can't use a hub for that. It does seem unlikely to work. For one thing, you'd have 2 or more controller devices connected together, which a hub is not designed for. Also, you'd need custom cables to connect them. Fokke -- Mark Lloyd http://notstupid.us/ "Death is an experience best avoided, as it makes reliable internet access difficult to obtain." |
#28
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USB Cable too long?
On 08/30/2018 01:00 PM, Fokke Nauta wrote:
[snip] Both pc's, on their turn, see that the scanner is on and recognize it. But only on my pc I am able to scan. Fokke The scanner could be getting confused, since it's connected to 2 different computers. Try resetting the scanner after switching. -- Mark Lloyd http://notstupid.us/ "Death is an experience best avoided, as it makes reliable internet access difficult to obtain." |
#29
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USB Cable too long?
On 08/30/2018 01:32 PM, Ken Blake wrote:
[snip] Have you tried using a hub for that, reversing its connections? I'm not saying that it will work, since I don't know and I also doubt it, but it might be worth a try. How would you connect it, to try that? USB (other than USB-C) uses different connectors for host and device. Let me ask why you want to do that. I sometimes move a thumb drive from a USB port of my computer to one on my wife's. It's easy enough to do that, so I've never the need for something like what you're talking about. My use for a USB switch is to quickly disconnect the keyboard when a cat jumps on it. -- Mark Lloyd http://notstupid.us/ "Death is an experience best avoided, as it makes reliable internet access difficult to obtain." |
#30
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USB Cable too long?
On 08/30/2018 01:56 PM, Fokke Nauta wrote:
[snip] No. How about the connecors, which need to be reversed as well? Cut 4 good USB cables in two to make the 3 custom cables needed to try something with a minuscule change of working. Let me ask why you want to do that. I sometimes move a thumb drive from a USB port of my computer to one on my wife's. It's easy enough to do that, so I've never the need for something like what you're talking about. We have one scanner and two pc's. We both want to use the scanner. In that case, I'd prefer a standalone scanner with a USB port or memory card slot. -- Mark Lloyd http://notstupid.us/ "Death is an experience best avoided, as it makes reliable internet access difficult to obtain." |
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