Hi
I'm looking for advice on the following problem. I'm using DMC-1886 galil card and 2 amplifiers AMP-19540 (8 motors altogether) . Old 1886 card has been damaged and when we replaced for new card the machine became uncontrollable. I loaded parameters onto eprom and that prevented motors from running away but plenty of issues still remains. The most disturbing is that for some reason polarity of IO has changed. What i mean by that is when i hit e-stop UI app shows green lamp(good) where in fact circuit is disconnected. Has anybody seen that before?
Galil_DJR on 09/05/2013 - 09:01
The 1886 has optically isolated inputs. The optos are bi-directional and will "activate" when current flows either direction between INCOM and the digital input. When there is no current flowing through the circuit, the input is "non active".
One key point is that a non-active input has a pullup. So therefore when the input is non-active, the pullup resistor makes it a "1". When the input is active, the value is "0". Some users think of this as reverse logic.
In the GalilTools watch, the following assignments are hard coded:
1 == Green == No current through opto
0 == Red == current through opto
If the color coding was reversed before on the old 18x6, you may have a different wiring in the circuit. For example, the sensor is now sourcing to ground at INCOM instead of snking from 5v at INCOM. This would account for a logic inversion.