Gecko 210 Help...

[Gads]

hi I started wiring my controller and am confused about the input option header pins on the Geckos. My BOB is a Campbell and from what i can tell from the doc is that it supplies 5v to Geckos. My Geckos appear to be set to common ground. Can anyone help explain this setting?
Thanks Gads

[Sparkman Stan]

If your set for common ground you need to supply +5 volts to terminal 10 to power the opto couplers. Thats for a parallel port which only switches to ground.

[mxtras]

It is confusing, but from what I have seen, pin 10 is +5VDC.

I see Mariss is watching - he is sure to post something to help out. It is a confusing point!

Search the zone for '5VDC Gecko' and 'schematic' and you will find many, many threads about this. Look for posts by Ynneb or CJL - these two have helped a lot of folks - including myself!

Scott

[Mariss Freimanis]

Common means 'shared' not 'ground' in electronics. Example: 'common anode', 'common collector', etc. 'Common ground' is a perfectly valid expression and is not redundant in this context.

Which setting to use? Most logic ICs do a much better sinking current (current flowing into an output and shunted to ground) than sourcing current (current flowing out from an output coming from the + supply). Here are some common logic family examples:

7400 16mA sink, 0.4mA source
74LS00 8mA sink, 0.4ma source
74S00 20mA sink, 1mA source
74HC00 4mA sink, 4mA source
74ACT00 24mA sink, 24mA source

Our drives require 16mA for the STEP and DIRECTION optoisolator LED currents to operate properly. From the above list:

7400, use 'common +5V' setting only.
74LS00, cannot be used at all.
74S00, use 'common +5V' setting only.
74HC00, cannot be used at all.
74ACT00, 'common +5V' or 'common Gnd' can be used. Best choice.

Mariss

[mxtras]

Thanks, Mariss.

Here's another thread with some pretty nice help about this and related issues:

http://www.cnczone.com/forums/showthread.php?t=18747

Scott