On 30.03.16 17:13, andy pugh wrote: > In the end, I fitted a different VFD which has a pre-written HAL driver. > It also only has two connections for RS485, so is less confusing. > I found a way to connect the dongle to the motherboard header: > https://forum.linuxcnc.org/forum/18-computer/30675-on-motherboard-modbus-rs485-connection > They are so cheap that I was prepared to go through a couple > experimenting, but it works fine.
Andy, That is an inspired solution to the ungrounded dangling-dongle problem - well worth emulating. Incidentally, is that cable in the last picture twisted pair? Shielded or no, is its characteristic impedance controlled? I wonder if the dongles have a 110 or 120 ohm termination, or you need to add that yourself? It's usual to put a 100 ohm resistor in a ground wire run between ends, to take up a difference due to leakage, but not cause big ground loops. That's in data networks - I can't say for sure it's least imperfect in a machine situation. Erik ------------------------------------------------------------------------------ Transform Data into Opportunity. Accelerate data analysis in your applications with Intel Data Analytics Acceleration Library. Click to learn more. http://pubads.g.doubleclick.net/gampad/clk?id=278785471&iu=/4140 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
