Yokogawa EJA438 - Manual (Page 42)

IM 1C22J1-01E 7-13
7. BRAIN TERMINAL BT200 OPERATION
(a) Follow the procedure below when setting the
present output to 0% (4 mA).
FEED NO OK
SET
J10:ZERO ADJ
0.0 %
CLR ESC
SET
J10:ZERO ADJ
0.0 %
+ 000.0 Press the key twice.
Zero adjustment is completed.
Press the (OK) key.
F0728.EPS
Output is 0.5%.
A10:OUTPUT (%)
0.5 %
Output is 0%.
A10:OUTPUT (%)
0.0 %
(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 glass gauge.
[Example]
Measurement range: 50 to 250 kPa, Actual value:
130 kPa.
Actual value
Actual
value(%)
x 100
130–50
250–50
= x 100=40.0%
–Measurement range lower range value
Measurement range higher range value
–Measurement range lower range value
=
(b)-1 Follow the procedure below to use J10: ZERO
ADJ .
CLR ESC
SET
J10:ZERO ADJ
0.0 %
+ 040.0 Enter the present actual level, 40%.
Press the key twice.
The output is changed to 40%.
F0729.EPS
Present output is 41.0%.
A10:OUTPUT (%)
41.0 %
A10:OUTPUT (%)
40.0 %
(b)-2 Follow the procedure below to use J11: ZERO
DEV .
ECS
ESC
SET
J11:ZERO DEV.
2.50 %
0 Since “J11: ZERO DEV.” contains
the previous correction, obtain the
correction value by adding –1.0% to
it. 2.50% + (–1.0%) = 1.50%
Set the correction value, 1.50.
Press the key twice.
F0730.EPS
Present output is 41.0%.
Output error = 40.0 – 41.0 = –1.0%.
A10:OUTPUT (%)
41.0 %
The output is changed to 40%.
A10:OUTPUT (%)
40.0 %
SET
J11:ZERO DEV.
2.50 %
1.50
(c) Zero Point Adjustment Using the External Zero
Adjustment Screw
• Enabling/inhibiting of zero point adjustment using
the external zero-adjustment screw on the transmitter
(J20: EXT ZERO ADJ)
Follow the procedure below to enable or inhibit zero
point adjustment from the zero-adjustment screw on
the transmitter.
This is set to “ENABLE” when the instrument is
shipped.
• Example: Inhibiting zero adjustment by the
external zero-adjustment screw
ESC
SET
J20:EXIT ZERO ADJ
ENABLE
< ENABLE >
< INHIBIT> Use the or key to
select “INHIBIT.”
Press the key twice to
enter the setting.
F0731.EPS
• Zero point adjustment using external zero-adjust-
ment screw on the transmitter
Turn the zero-adjustment screw on the outside of the
transmitter case using a slotted screwdriver. Turn the
screw to the right to increase the zero point or to the
left to decrease the zero output; the zero adjusts in
increments of 0.01% of the range setting.
Note that the amount of adjustment to the zero point
changes according to the speed at which the screw is
turned. To make fine adjustments, turn the screw
slowly; to make coarse adjustments, turn the screw
quickly.
Note: When a zero point adjustment has been made, do not turn
off the transmitter less than 30 seconds after adjustment.