Yokogawa EJX440A - Manual (Page 22)

IM 01C25T03-01E 3-14
3. OPERATION
• Example 2: When the upper range value is to
be changed to 10 kPa with the
present setting of 0 to 30 kPa, take
the following action with an input
pressure of 10 kPa applied.
FEED NO OK
SET
H11:AUTO URV
10.000 kPa
DATA DIAG PRNT ESC
PARAM
H10:AUTO P LRV
0 kPa
H11:AUTO P URV
10.000 kPa
H20:AUTO SP LRV
0.0 MPa
ESC
SET
H11:AUTO P URV
30 kPa
+ 30
The lower range value is not
changed, so the span changes.
Parameter C22 is changed at the
same time.
Press the key twice.
The upper range value is changed
to 10 kPa.
Press the (OK) key.
F0330.EPS
(15) Sensor Trim
Each DPharp EJX series transmitter is factory charac-
terized. Factory characterization is the process of
comparing a known pressure input with the output of
each transmitter sensor module over the entire pressure
and temperature operating range. During the character-
ization process, this comparison information is stored
in the transmitter EEPROM. In operation, the transmit-
ter uses this factory-stored curve to produce a process
variable output (PV), in engineering units, dependent
on the pressure input.
The sensor trim procedure allows you to adjust for
local conditions, changing how the transmitter calcu-
lates process variables. There are two ways to trim the
sensor: a zero trim and a full sensor trim. A zero trim
is a one-point adjustment typically used to compensate
for mounting position effects or zero shifts caused by
static pressure. A full sensor trim is a two-point
process, in which two accurate end-point pressures are
applied (equal to or greater than the range values), and
all output is linearized between them.
a. Zero Trim
(J11: P ZERO ADJ, J15: P ZERO DEV,
J55: EXT ZERO ADJ)
The DPharp supports several adjustment methods.
Select the method best suited for the conditions of your
application.
Adjustment Method Description
Using the BT200 Set the present input to 0%.
Using the external
zero-adjustment
screw Adjust zero point using the zero-
adjustment screw on the transmitter.
This permits zero adjustment without
using the BT200. Accurately adjust
the output current to 4 mA DC or
other target output value using an
ammeter that accurately reads output
currents.
Adjust output to the reference value
obtained using other means.
Adjust for 0% output at input level of
0%.
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 sight glass.
T0307.EPS