Rockwell Automation System Design for the Control of Electrical Noise - Manual (Page 85)

Publication GMC-RM001A-EN-P — July 2001
High Speed Registration Inputs 9-9
Figure 9.8
Registration Error vs. Delay (rotary units)
Error Compensation
If the registration signal delay is constant, it will have the effect of
applying a position error proportional to velocity. In this case it may
be possible to apply a software correction.
Software Solutions
It is possible to increase noise resistance with your software,
especially if the problem is false triggering on the falling edge (which
is usually much slower than the rising edge).
Try one of the following techniques before re-arming or looking for
the next registration event.
• Add wait-for-registration-input-low.
• Add a timer after a registration event (to allow the switch signal to
go low).
• Add wait-for-position-greater-than-x (to allow the switch signal to
go low).
0.0001
0.001
0.01
0.1
1
10
20 50 100 200 500 1000 2000
Velocity RPM
Error de
g
1 uS 2 uS 5 uS 10 uS
20 uS 50 uS 100 uS