USB to RS-485

I'm looking for a USB to RS-485 converter for my robot's bus.
I did a google search and it displayed a few of them, but none that
satisfies all of my requirements. Here they are: - Powered out of the USB port - Small - Cheap
The above requirements are purposefully vague, I assume that you will contextualize them in a mobile robot base (12x18 inches).
The one I liked most (USB-COMi) requires a wall wart...
I'm avoiding making my own USB or RS232 converter, but I think I'll have to if I don't find one that suits me.
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Padu wrote:

Unless the power requirement is bizarre, why not just make your own power supply in lieu of the wall wart?
I've been known to purchase wall wart-powered stuff only to cut the power cable from the wart in half and add mating connectors to both severed ends so that I can power the device either from my own supply (with a matching connector) OR from the wart.
Should be easier in any case than making your own converter, if substantially less entertaining.
Hope that helps -- tafkakS
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"The Artist Formerly Known as Kap'n Salty"

That's an option too, definitely better than doing my own converter, but not better than USB power supplied... I think I had not looked hard enough. EasySynch does a USB-COMi-M which is USB powered, small and not so expensive ($70 the non-opto isolated and $100 the opto isolated).
I'll continue searching for the next 2 days, if I don't find anything better, I'll get this one.
Thanks
Padu
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On Mon, 23 May 2005 14:03:10 -0700, the renowned "Padu"

That's not what their data sheet says:
http://www.dghcorp.com/usb-COMi.pdf
"Bus-powered. No external power supply needed."
It can't do MODBUS RTU so the timing must be sloppy (perhaps comes with the territory).

Best regards, Spehro Pefhany
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"Spehro Pefhany"

But that's what their user manual says: (top of page 3)
http://www.easysync.co.uk/documents/USBCOMmanual.pdf
"Power Supply -An external power adapter are required. -- The USB-2COMi, USB-2COMi-SI, USB-4COM, USB-4COMi,USB-8COM are provided with an external power adapter in the package. You need to plug the power adapter to the power source first before driver installation.
I wonder which one is right.
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Padu wrote:

Notice that the USB-COMi is not on the list.
I have a three-device RS-485 bus that runs off of this device. -- D. Jay Newman http://enerd.ws/robots
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Padu wrote:

have a look at: http://www.dontronics.com//usb_485.html
they are definitely usb powered, and price is approx $65USD inc postage. in stock, ready to ship
Don...
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E-Mail Contact Page: http://www.e-dotcom.com/ecp.php?un=Dontronics
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Don McKenzie wrote:

plug
installation.
postage.
http://www.e-dotcom.com/ecp.php?un=Dontronics
http://www.dontronics.com/micro-vga.html
http://www.dontronics.com/usb_232.html
Another option, just need to att the TTL to RS232 line convertor IC...
http://www.active-robots.com/products/accessories/act-sib.shtml
Mark
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Spehro Pefhany wrote:

Mine doesn't require a wall wart. And you can make it much smaller if you take it out of the plastic container. -- D. Jay Newman http://enerd.ws/robots /
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