Trigger generator accuracy of rabbit RCM3200 processor

hello sir,
I interface RCM3200 series with Trigger generator .Ur machine speed=600 m/min. and cylinder circumference=600 mm. So encoder RPM:-1000=>16.666 rev/sec.
1 encoder pulse per 60 usec.

If ,we scan encoder pulse and compare gate position at 120 usec,execution time comes to 1/3 of scan time,so we sacrifies trigger position by 1 to 2 encoder pulse =>0.6 to 1.2 mm.

What will be better solution ?.