On 3/2/2014 3:20 AM, Steve Blackmore wrote: > 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 > -- >
Allen Bradley and Siemens have fully embraced Ethernet as their standard interface. Siemens new small PLCs(S7-1200's) only have an Ethernet port. And they work fine.. Everytime I use one of them I wonder why didn't the Industrial Automation industry jump on Ethernet 10 years earlier. I have a bag full of unique RS232/485/Current loop cables for different old PLC interfaces and that is aside from the oftentimes needed USB to serial adapters.. not fun. Dave ------------------------------------------------------------------------------ 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
