Instruction Manual
D103785X012
Calibration
June 2017
42
Travel Calibration
If a double‐acting relay is used, you will be prompted to run the relay adjustment when auto or manual calibration is
selected. Select Yes to adjust the relay, select No to proceed with calibration. For additional information, refer to Relay
Adjustment on page 52.
Auto Calibration
User interaction is only required with Auto Calibrate Travel when the feedback connection is SStem ‐ Standard (Sliding
Stem ‐ Standard). A feedback connection of Rotary ‐ All, SStem ‐ Roller (Sliding Stem ‐ Roller) requires no user
interaction and you can start with step 6.
For a SStem ‐ Standard feedback connection, interaction provides a more accurate crossover adjustment. Setting
crossover establishes the zero degree point for the geometric correction used to translate the rotary motion observed
by the travel sensor into the linear motion of the sliding‐stem valve.
1. Select the method of crossover adjustment: manual, last value, or default. Manual is the recommended choice. If
you select Manual, the Field Communicator will prompt you to adjust the crossover in step 3.
If you select Last Value, the crossover setting currently stored in the instrument is used and there are no further user
interactions with the auto‐calibration routine (go to step 6). Use this selection if you cannot use manual, such as
when you cannot see the valve.
If you select Default, an approximate value for the crossover is written to the instrument and there are no further
user interactions with the auto‐calibration routine (go to step 6). Use this selection only as a last resort. Default
assumes a midrange position on the travel sensor as the crossover point, however, this may not be an appropriate
value to use for crossover because of variations in mounting and travel sensor calibration.
2. The instrument seeks the high and low drive points and the minor loop feedback (MLFB) and output bias. No user
interaction is required in this step. For a description of these actions see step 6.
3. If you select Manual in step 1, you are asked to select an adjustment source, either analog or digital. If you use a
4. If you selected Analog as the crossover adjustment source, the Field Communicator prompts you to adjust the
current source until the feedback arm is 90
°
to the actuator stem, as shown in figure 4‐1. After you have made the
adjustment, press OK and go to step 6.
5. If you selected Digital as the crossover adjustment source, the Field Communicator displays a menu to allow you to
adjust the crossover.
Select the direction and size of change required to set the feedback arm so it is 90
°
to the actuator stem, as shown
in figure 4‐1. Selecting large, medium, and small adjustments to the crossover causes changes of approximately
10.0
°
, 1.0
°
, and 0.1
°
, respectively, to the rotation of the feedback arm.
If another adjustment is required, repeat step 5. Otherwise, select Done and go to step 6.
6. The remainder of the auto calibration procedure is automatic. It is completed when the
Calibration
menu appears.
During calibration, the instrument seeks the high and low end points and the minor loop feedback (MLFB) and
output bias. By searching for the end points, the instrument establishes the limits of physical travel, i.e.
the actual
travel 0 and 100% positions. This also determines how far the relay beam swings to calibrate the sensitivity of the
MLFB sensor.
