On Sat, 01 Mar 2014 21:19:06 -0500, you wrote: >I've had a number of problems when plugging into industrial devices that >have a USB interface. The lack of isolation is oftentimes a problem. >Othertimes my laptop will confuse the industrial device with another >common USB device like a stick drive, even if the driver for the >industrial device has been loaded. >I've never had similar issues with RS232 or Ethernet interfaces.
The idea behind USB is good but is often let down by OEM penny pinching on design, firmware and software. Many devices simply do not meet USB standards and the myriad of different things a USB device could be can make it a lottery sometimes. Laptops are particularly bad - hidden power saving that you can't disable, even via bios and half baked hardware, like you say with isolation, or alternately a lack of ground problem. I've seen the confusion problem too, not only with laptops. "Plug and pray" sometimes doesn't. Again, crappy hardware, power saving or driver problems. The most common fix is always install any supplied drivers WITHOUT the device plugged in. Also cycling the power by shutting down then removing batteries, and/or mains for a few minutes often fixes confused PC's. RS232 is becoming rare on modern devices, it's slow and single ended and relies on a common signal ground between devices. That can introduce it's own problems. Ethernet is complex and needs careful design to work at all - hence it's expensive. See http://www.iebmedia.com/index.php?id=8777&parentid=74&themeid=255&showdetail=true Steve Blackmore -- ------------------------------------------------------------------------------ Flow-based real-time traffic analytics software. Cisco certified tool. Monitor traffic, SLAs, QoS, Medianet, WAAS etc. with NetFlow Analyzer Customize your own dashboards, set traffic alerts and generate reports. Network behavioral analysis & security monitoring. All-in-one tool. http://pubads.g.doubleclick.net/gampad/clk?id=126839071&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
