Rockwell Automation 1771-QB Linear Pos. - Manual (Page 125)

Initializing and Tuning the Axes
Chapter 8
8Ć7
You should verify the analog output polarity using low speed open-loop jogs as
follows:
ATTENTION: Incorrect analog output polarity will cause the axis to
accelerate out of position when then loop is closed. The analog
output polarity is affected by both the wiring on terminals 29/31 and
the sign of the analog range in the parameter block.
1. Turn off axis power.
2. Disconnect the transducer gate leads from the wiring arm terminals 1/3.
3. Start the hydraulic pump.
4. Apply power to the I/O chassis, the analog output, the transducer interface
and the discrete inputs. Don’t power the axis that you are not integrating.
5. Clear bit 2 at N45:131 to place the axis in manual mode. Use the forward
and reverse jog bits in axis control word 1 of the command block (bits 5
and 6 at data table address N45:131) to command jogs in the positive and
negative directions. Check that a forward jog moves the axis in the
positive direction as defined by the zero-position offset, and a reverse jog
moves the axis in the negative direction.
6. If the direction of motion is incorrect, either reverse the analog
connections at the module wiring arm or change the sign of the analog
range word in the parameter block. Recheck that the direction of motion is
correct.
7. Turn off axis power and the hydraulic pump.
8. Re-connect the transducer gate leads to the wiring arm terminals.
The module uses the transducer calibration constant to convert pulses received
from the transducer to a position in real world units. The transducer constant is
usually stamped on the side of the transducer. However, sometimes the stamp is
not easily accessible or you may not be confident that it is accurate. You can use
the following procedure to determine the transducer calibration constants for the
transducers.
You will need a six inch or longer caliper to measure axis position. The length
and accuracy of the caliper determines the accuracy of the transducer calibration
constant. Longer or more accurate instruments will produce better results.
1. Use Table 8.B to determine your initial guess, based on the number of
circulations programmed into the digital interface box.
Verifying Analog Output
Polarity
Verifying Transducer
Calibration Constants