Experimental Physics and
Industrial Control System

Benjamin Franksen <[email protected]> · Thu, 21 Aug 2008 13:50:55 +0200

On Thursday 14 August 2008 18:10, Kurt Goetze wrote:
> It would be dangerous to automatically override soft limits for a homing
> operation, in my opinion.  If soft limits had been set within the home
> position,
> and a decision was made to home the positioner, then some human
> intervention
> would be needed to decide whether the situation that the soft limits
> were set
> to protect against is still valid.  If a positioner is to be expected to
> *always* be ready for a homing operation, then the soft limits should
> be set and left outside of the home position.

This assumes that the current position information is somehow still valid, 
at least approximately. However, tehre is no guarantee taht this is so 
before the motor gets homed. Thus, I agree that soft limits make no sense 
during home operation.

> Also, if a positioner is homed accidentally, before any obstructions were
> cleared out of the way, it would be good to know that the soft limits
> will do
> their job.

Again, in general they can't. Thus all you get is a false sense of security.

Cheers
Ben
-- 
"Programming = Mathematics + Murphy's Law" (E.W.Dijkstra)

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System