Yokogawa EJA115 - Manual (Page 49)

IM 01C22T02-01E A-11
APPENDIX 2. APPLICATION, SETTING AND CHANGE OF BASIC PARAMETERS
(a) Perform the following procedure to set the
current output value to 0%.
Set the input pressure to zero.
FA0211.EPS
Access the TRIM_PV_ZERO parameter.
When 0.0 is written, adjustment is performed
to set the current input pressure to zero.
Note: TRIM_PV_ZERO allows only 0 to be executable.
Access the TRIM_MODE parameter.
Set Trim disable
Access the TRIM_MODE parameter.
Set Trim enable.
(b) In tank level measurement, if the actual level
cannot be brought to zero for zero adjustment,
then the output can be adjusted to correspond
to the actual level obtained using another
measuring instrument such as a sight glass.
Current level: 45%
Current output: 42% (output range value)
Current setting of calibration range: 0 - 100kPa
In order to adjust the current output with the actual
level, it is necessary to shift current output so as to
indicate the actual correct level with the
XD_SCALE parameter. For details of how to set the
XD_SCALE parameter, refer to “Setting the output
scale” in Section A2.3 (2).
(c) Zero-point adjustment using an external zero-
adjustment screw
If zero- adjustment by means of adjustment screw is
permitted, perform adjustment by turning the screw.
FA0212.EPS
Set Auto to the Target parameter in block mode
(MODE_BLK).
Perform zero-point adjustment by using a
standard screwdriver to turn the zero-
adjustment screw mounted outside the
equipment case.
Access the EXT_ZERO_ENABLE parameter.
Write 0 and permit setting beginning with
external zero-point adjustment.
Turning the screw clockwise causes the output value
to increase while turning it counterclockwise causes
the output to decrease; zero-point can be adjusted
with a resolution of 0.001% of URV.
The amount of zero-point adjustment changes
according to the speed at which the zero- adjustment
screw is turned; turn it slowly for fine tuning, or
quickly for coarse tuning.