Yokogawa EJX530B - Manual (Page 53)

<8. Setting Parameters>
8-20
IM 01C27F01-01EN
(1) Zero Point Adjustment
a. To set 0% at current input, perform
following procedure.
This method is used only when the pressure at
bottom of measurement range is zero.
• Procedure to call up the lower limit adjustment
parameter (Calibration Lowest Point).
AI1 block : Calibration Lowest Point
Set 0 to Calibration Lowest Point parameter for
pressure (AI1 block).
• Procedure to call up the calibration adjustment
parameter (Cal Cmd).
AI1 block : Cal Cmd : CAL_LOW
Lower limit is changed by using Cal Cmd
parameter for puressure (AI1 block).
• Procedure to call up the calibration adjustment
parameter (Cal Status)
AI1 block: Cal Status
Confirm the calibration status of CAL_
SUCCESS (1) using the Cal Status parameter.
b. To match current input and output value,
follow procedure
Like the measurement that is impossible to
set process pressure to 0kPa, output value is
adjustment to actual level by other measurement
using glassgage.
Example:
Pressure Transmitter’s span is 0 to 25.00kPa,
current level is 13.50kPa, current output is
13.83kPa.
• Procedure to call up the lower limit adjustment
parameter (Calibration Lowest Point).
AI1 Block: Calibration Lowest Point
Set the actual level value of 13.50 kPa to the
Calibration Lowest Point parameter for the
pressure (AI1 block). Apply an actual input
and confirm the value specified in Calibration
Lowest Point as the output value.
• Procedure to call up the calibration adjustment
parameter (Cal Cmd).
AI1 block: Cal Cmd: CAL_LOW
The present output is changed from 13.83kPa
to 13.50 kPa in CAL_LOW of the pressure (AI1
block) Cal Cmd parameter.
• Procedure to call up the calibration status
parameter (Cal Status).
AI1 block: Cal Status
Confirm the calibration status of Cal Status (1)
using the Cal Status parameter.
c. Using External Zero adjustment Screw
External Zero-adjustment parameter (External
Zero Trim) can set permission or prohibition to
adjustment by External Zero-adjustment Screw.
Set “Trim on” to use the External Zero-adjustment
Screw. (“Trim on” at shipment)
Use a slotted screwdriver to turn the zero-
adjustment screw. Equalize the transmitter, then
turn the screw clockwise to increase the output or
counterclockwise to decrease the output. The zero
point adjustment can be made with a resolution
of 0.01% of the setting range. The degree of zero
adjustments varies with the screw turning speed;
turn the screw slowly to make a fine adjustment,
quickly to make a rough adjustment.
Zero-adjustment Screw
F0806.ai
Figure 8.2 Zero-adjustment Screw