[bbutcher85710]

That may all be true with Mach3 using the parallel port. However according to Galil documentation (DMC1700-1800 User Guide) the Optima board captures the encoder position within 25 micro seconds of contact. From the users guide:

"Often it is desirable to capture the position precisely for registration applications. The DMC-
1700/1800 provides a position latch feature. This feature allows the position of the main or auxiliary
encoders of X,Y,Z or W to be captured within 25 microseconds of an external low input signal. The
general inputs 1 through 4 and 9 thru 12 correspond to each axis."

This encoder position is reported to Mach3 by the plugin. The accuracy of the location will be a function of the speed of course. For my system I move at a rate of 4 inches per minute, or 0.066 inches per second. Thus a delay of 25 microseconds will result in an error of positon of 0.000000066 inches, which is far better than Mach3 can resolve. .
This is another advantage of using a dedicated processor to handle the motion, but it does make the configuration a bit more messy. All PID motor tuning is also handled by the Optima board, and must be done outside Mach3.

[mactec54]

That may all be true with Mach3 using the parallel port. However according to Galil documentation (DMC1700-1800 User Guide) the Optima board captures the encoder position within 25 micro seconds of contact. From the users guide:

"Often it is desirable to capture the position precisely for registration applications. The DMC-
1700/1800 provides a position latch feature. This feature allows the position of the main or auxiliary
encoders of X,Y,Z or W to be captured within 25 microseconds of an external low input signal. The
general inputs 1 through 4 and 9 thru 12 correspond to each axis."

This encoder position is reported to Mach3 by the plugin. The accuracy of the location will be a function of the speed of course. For my system I move at a rate of 4 inches per minute, or 0.066 inches per second. Thus a delay of 25 microseconds will result in an error of positon of 0.000000066 inches, which is far better than Mach3 can resolve. .
This is another advantage of using a dedicated processor to handle the motion, but it does make the configuration a bit more messy. All PID motor tuning is also handled by the Optima board, and must be done outside Mach3.

Mach3 does not work well with Galil there are many problems with it, Mach4 I believe has a plugin for the Galil but don't know how well it works