On 22.01.16 10:08, andy pugh wrote: > I was having trouble sleeping last night, I was obsessing about CNC > machine wiring. > In an attempt to break the cycle I went on eBay and bought > http://www.ebay.co.uk/itm/291551363807 > > In the cold light of day I think I made a mistake.
Creative synthesis of a problem solution by the subconscious at night = good. Making reasoned choices in the same time frame = rubbish. ( Don't ask how I've reached that conclusion.) > I wanted to control the two clutches and the brake on my lathe > gearbox. These have a single wire to a brush (24V) and return via the > machine frame. s/These have/These each have/ ? > I don't think that this device can be wired to operate them unless I > create a separate -24V supply by wiring the +24 of a PSU to the > machine frame. Yes, that was my first reaction to seeing the negative common on the DC SSR. If it's implemented with optocouplers + N-channel FETs, then that's expected. There is a way to use low-side switches. Burrow into each solenoid device to isolate the frame return, and switch that. (I figure you've already briefly considered that.) Three individual DC SSRs could operate as high-side switches. (An optocoupler, two resistors, a zener, and a power MOSFET, should suffice to DIY, if the opto's transistor is used to hold the FET off. Hmmm, loss of signal would then turn them all on - maybe not good?) > I also don't think that it is particularly well suited to being driven > by the 7i84 outputs. If the 7i84 won't take 24v, then a transistor and two resistors, per output, fixes that. Erik ------------------------------------------------------------------------------ Site24x7 APM Insight: Get Deep Visibility into Application Performance APM + Mobile APM + RUM: Monitor 3 App instances at just $35/Month Monitor end-to-end web transactions and take corrective actions now Troubleshoot faster and improve end-user experience. Signup Now! http://pubads.g.doubleclick.net/gampad/clk?id=267308311&iu=/4140 _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
