Rockwell Automation 1771-QB Linear Pos. - Manual (Page 86)

Formatting Module Data (WRITES)
Chapter 7
7Ć7
Figure 7.4
Analog Calibration Constant Words
50027
Analog calibration constant for positive motion,
BCD 99.99 ips or 999.9 mmps max
Binary 327.67 ips or 3276.7 mmps max
Analog calibration constant for negative motion,
BCD 99.99 ips or 999.9 mmps max
Binary 327.67 ips or 3276.7 mmps max
Note: ips = inches per second
mmps = millimeters per second
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For servo valves, the analog calibration constants can be roughly calculated
from the diameter of the cylinder and the maximum flow rate of the valve. You
will fine-tune these parameters when you perform the tuning procedure given in
Chapter 8.
Transducer Calibration Constant (words 5, 6 and 34, 35)
The module uses the transducer calibration constant to convert the transducer
generated pulse width into an axis position reading.
Calculate the transducer calibration constant by multiplying the figure stamped
on the side of the transducer head by the number of circulations that you are
using. This figure varies slightly from one transducer to another. It is typically
9.0500 microseconds per inch or 0.35600 microseconds per millimeter.
Example: If your transducer is stamped with 9.0500 microseconds per inch
and you’ve programmed your digital interface box for four circulations, your
transducer calibration constant would be:
4 x 9.0500 = 36.2000
See Chapter 4 to determine the optimum number of circulations for your system
and Chapter 8 for a procedure for verifying the transducer calibration constant.