Delta RMC101 - Manual (Page 573)

MDT 6.2
Transducer Interface Modules 6-29
following table shows the possible Scales and Prescale Divisors you could use and the effective
scale:
Scale Divisor Effective
Scale Error from
6324.70
6325 1 6325/1 =
6325 0.005%
12649 2 12649/2 =
6324.5 0.003%
25299 4 25299/4 =
6324.75 0.0008%
50598 8 Invalid scale Invalid
Therefore, in this example, a Scale of 25299 and a Prescale Divisor of 4 should be used. If the
Scale you calculate comes to 32768, enter 0 instead.
These calculations can be done automatically using the Position Scale/Offset Calibration Utility
feature in RMCWin.
Method 2: Using the MDT Calibration Number
The Scale can also be calculated using the MDT calibration number (nominally 9.012
microseconds per inch) with the following formula. Notice that the Prescale Divisor is left out at
this point; it is calculated after the initial Scale value has been calculated, as described in Method
1:
In the above formula, the 120MHz comes from the RMC’s internal counter, and Sign equals +1
when an extend move yields increasing Actual Position counts, and -1 when an extend move
yields decreasing Actual Position counts. The calibration number must be specified in the same
units as the Position Units (inches, mm, etc.). Position Units are generally 0.001 inches or 0.1
mm. Usually there are 1000 Position Units per inch when the calibration number is in
microseconds per inch.
Once the Scale and Prescale Divisor have been calculated, the Offset can be calculated:
These calculations are done automatically using the MDT Scale/Offset Calibration Utility feature
in RMCWin.
Example 1
A system has an MDT with a calibration number of 9.1392 ms per inch and 1 recirculation. The
desired position units are thousandths of an inch. Therefore, there are 1000 position units per