USB to RJ-45 console cable?

USB is 4-conductor plus the shell, and the only things I've seen ready-made are USB ethernet adapters, which include electronics you don't want. But any custom shop can make one for you, or you could do it yourself as you describe.

Oh, here's something:

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Hi All,

I know have read numerous threads on Google goups and cannot come up with an answer on this one.

I have already read and seen that there are cables/adapters that go from USB to DB-9. That would allow you to connect your standard serial console cable as you normall would. I am trying to find a way to eliminate this.

I would like to buy/make a cable that will have a USB connector on one end and an RJ-45 on the other. I'm not sure if it is as easy as cutting off a connector on the usb and just terminating the RX/TX/GND like you can do with a serial cable (DB-9).

I know there may be some issues with going from USB to rs-232 signaling and I could always build some kind of breakout box in the middle.

Any thought?????

- Jay

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What are you trying to do with this adapter? There are USB to

8pin modular adapters already used in the security system market, allowing cheap USB cameras to feed to a PC rather than much more expensive dedicated security type cameras and video logging systems. These devices are also being used in the AV world for extending USB mice to the lectern from the PC running the power point presentation back at the tech table. As for USB to a RS 232 serial port, then you will need some active electronics. I don't know if someone makes one, but I expect there is one out there. --Dale
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Dale Farmer

A USB device will not talk directly to an RS-232 without use of a special converter that would buffer the data, format is differently and send over the other interface. There are devices out there (check out ads in pretty much any industrial/hobby electronics-related publication) with USB on one end and RS-232 on the other, within $75-$100 range. You will have to worry about the actual connections yourself: most I've seen have either straight headers or screw terminals.

Speaking of USB-to-RJ45 though: APC's UPSes are connected to PCs with exactly the same cable. This is not to say that it has anything to do with conversions; there is non done in the cable as the UPS is looking for a USB signal, but the point is: if you grab a hold of a cheap 350VA unit that does not have to get hooked up to a PC (like, a one used to protect a KSU or some other device without USB), you can borrow a nice 4ft factory made cable with USB connector on one end and 8P8C (often referred to as RJ45) on the other. Completely proprietary pinout, but what do you care? You'll have to come up with your own anyways, so why not to use APCs?

Good luck!

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No it is *not* that simple. You need the 'goodies' that are in the cable you won't buy.

You cannot build one for the price you can buy a USB-RS-232 adapter cable for.

just go buy one.

You _can_ just cut off the DB-9 end of such a cable, and replace it with an "appropriately wired" RJ-45. Assuming the wires in the cable are small enough guage to _fit_ in a RJ connector. You -do- need to worry about more than just TX/RX/GND. CTS, RTS, DCD, DSR, and DTR need to be considered, too.

Reply to
Robert Bonomi

Try this link, I have one of these, it works great!!

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Mikey B.

Bought one for my new laptop that has no serial port. Imagine my dismay when I found the thing was not programmable as DCE or DTE. Still have to carry around null modem cables and gender adapters. And the laptop ! A giant, too large and too heavy, have not yet found an equipment room with enough clear space to set it up. Ends up on the floor.


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Okay, I think I may have missed something here, but I stumbled across this post looking for (I believe) the same thing the OP was, but then I see links to USB/DB9 converters and someone talking about power supplies, so if I've missed something, I apologize. I was hoping to find a way to skip the USB/DB9 adapters and build a straight forward cable which would allow connecting between a USB port on my laptop/tablet and a console port on a piece of equipment like a cisco switch. I don't know what all that would require (hence why I am looking), but I've got cables, crimpers and RJ-45s. "Beware programmers who carry screw drivers." If I am understanding anything/everything/something then the OP was looking for the same and the general consensus among those who seem to be talking about the same thing is that it is worth it to buy the cable since a direct USB/RJ-45 conversion isn't possible without some extra components. Did I get it or miss something here?

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You got it. The internal hardware and software protocol for USB is very different from that for a serial port.

If you search online for usb to serial converter, you can find lots of them under $10.

Reply to
John Levine

I assume the mention of serial cable means that both of you are looking for a USB to serial with RJ-45 connector on it. As opposed to something like a USB to ethernet with an RJ-45 connector on it.

I don't think you could find a USB to serial dongle that doesn't have the electronics actually located in the DE9 head end of the device. If you cut that off, you'd end up with a broken USB plug.

While, USB to TTL line level serial cables are pretty popular (ie. see line from FTDI), especially for the electronics hobbist that routinely can use them, USB to RS-232 level serial cables are pretty rare, but they do exist.

I bought a batch of them directly from Shenzhen. They use SiLabs chips and the electronics, with RS-232 line level converter chip all exist in the USB plug end of the cable. There is no dongle in the middle, just a USB plug with an RJ-45 on the other end.

I've been toying around with buying a bigger batch and selling them on eBay or something. :-)

There seems to be like minded people that want them. They work against all my Cisco/Juniper/Sun/Fortinet gear.

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