Yokogawa EJA115 - Manual (Page 4)

IM 01C22T01-01E 1-1
1. ZERO POINT ADJUSTMENT
1. ZERO POINT ADJUSTMENT
After operating preparation is completed, adjust the
zero point. The zero point adjustment can be made
using either of the following two methods.
For output signal checking, display the parameter %
rnge in the HART Communicator.
HART Communication
display
EJA:
Process variable
1 Pres
0.012nnH2O
2 % range 0.00%
3 A01 Out 4.002mA
4 Snsr temp 38.1C
5 Static pres
HELP DIAG HOME ESC
F0101.EPS
Zero-adjustment
screw
᭿
Using the Transmitter Zero-adjustment
Screw
Before using the zero-adjustment screw outside the
transmitter case, confirm the following.
• Ext SW mode must be ENABLE . See Subsection
2.3.3 (17) for the setting procedure.
• Use a slotted screwdriver to turn the zero-adjustment
screw. Turn the screw clockwise to increase the
output or counterclockwise to decrease the output,
the zero point adjustment can be adjusted with a
resolution of 0.01% of the setting range.
The degree of zero adjustments varies with the
screw turning speed. Therefore, turn the screw
slowly for fine adjustment and quickly for coarse
adjustment.
CAUTION
Do not turn off the power to the transmitter
immediately after a zero adjustment. Powering
off within 30 seconds after a zero adjustment will
return the adjustment back to the previous
settings.
᭿
Using the HART Communicator
Zero point can be adjusted by simple key operation of
the HART Communicator.
Select parameter Zero Trim , and press the OK (F4)
key twice. The zero point will be adjusted automati-
cally to the output signal 0% (4 mA DC). Confirm that
the setting value displayed for the parameter
% rnge
is 0.0% before pressing the OK (F4) key. See Subsec-
tion for HART Communicator operating procedures.
1.1 Zero Point Adjustment
The DPharp supports several adjustment methods.
Select the method best suited for conditions matching
the state of the site.
Note that output signal can be checked by HART
Communicator.
Adjustment Method Description
Zero adjustment
using the HART
Communicator Set the present
input to 0%.
P.1-2 ‘Zero trim’
Zero adjustment
using the
external zero-
adjustment
screw Adjust zero point using the zero-
adjustment screw on the transmitter.
This permits zero adjustment without
using the HART Communicator.
Accurately adjust the output current to
4mA DC or other target output value
using an ammeter that accurately reads
output currents.
Adjust for 0% output
at input level of 0%.
Adjust output to
the reference
value obtained
using other
means.
P.1-2 ‘Lower
sensor trim’ If the input level
cannot easily be
made 0% (because of
tank level, etc.),
adjust output to the
reference value
obtained using other
means, such as a
glass gauge.
T0101.EPS