IM 01C25R03-01E
6-4
6. EXPLANATION OF BASIC ITEMS
Adjustment of static pressure signal:
The zero/span adjustment function can be used for
static signals, as in the case of differential pressure
signals. However, the zero-point adjustment by the
external screw function is not supported for static
pressure signal.
Automatic adjustment
The value of the static pressure exerted on the point
where adjustment is to be made is assigned to param-
eters (CAL_SP_POINT_LO, CAL_SP_POINT_HI).
After this assignment is set, the amount of adjustment
is calculated by the transmitter and automatically
updated. The procedure for adjusting the static pressure
signal is the same as that of differential pressure signal.
Manual adjustment
From the exerted pressure and the output of the
transmitter, calculate the amount of zero/span adjust-
ment manually and assign the calculated value to
parameters (CAL_SP_DEVIATION_LO,
CAL_SP_DEVIATION_HI).
Selection of static pressure signal type:
EJX910A transmitter measure the absolute static
pressure. Based on the assumption that atmospheric
pressure is constant, these transmitters can output
signal equivalent to gauge pressure calculated by
deducting the atmospheric pressure (fixed value) from
the measured absolute pressure. The type of static
pressure signal output to SECONDARY_VALUE and
TERTIARY_VALUE is selected in
SP_VALUE_TYPE. SP_VALUE_TYPE allows
selection of gauge pressure or absolute pressure. When
selecting gauge pressure, set the value of the atmo-
spheric pressure (fixed value) to ATM_PRESS. The
default value of ATM_PRESS is equal to the value of
standard atmospheric pressure (101.325 kPa).
Atmospheric pressure automatic setting:
When “Set” is set to the
CURRENT_ATM_PRESS_ENABLE parameter, the
present L-side static pressure can be automatically
assigned as the atmospheric pressure (ATM_PRESS).
To make this assignment, the SENSOR transducer
block must be set to the O/S mode. After the L-side
static pressure has been assigned to ATM_PRESS, the
value of CURRENT_ATM_PRESS_ENABLE auto-
matically returns to “off”.
6.3.5 Functions Relating to External
Temperature
Reference to external temperature value:
The contact temperature and status of the RTD
connected at EXT_TEMP_VAL can be referenced. The
update period of this value is about 800 mS. The
external temperature unit is the unit selected at
XD_SCALE.Unit in the AI block where
EXT_TEMP_VAL is selected. Usually, the status
indicates Good-Non Specific; however, it changes to
Bad or Uncertain during a sensor malfunction or when
the measuring range is exceeded. For actual details, see
Table 8.9 Parameter Operations at Error Occurrence.
Assignment of the damping time constant of the
external temperature signal:
The EXT_TEMP_VALUE_FTIME parameter is for
setting the damping parameter of the external temperature
signal. The setting unit for this parameter is [seconds].
Judgment of range limit of the external tempera-
ture signal:
When the external temperature signal has deviated
from the measuring range (-200 to 850ºC) by 85ºC or
more, it is outside the external temperature specifica-
tion range, and the status of the external temperature
signal (EXT_TEM_VAL) is set to Uncertain-Sensor
Conversion not Accurate.
Adjustment of external temperature signal:
A zero/span adjustment function is available for the
external temperature signal just like for the pressure
(differential pressure) signal.
Automatic adjustment
The temperature value is assigned to parameters
(CAL_EXT_TEMP_LO and CAL_EXT_TEMP_HI)
with the external temperature sensor immersed in the
temperature to be adjusted. After this assignment is
made, the adjustment amount is calculated internally by
the transmitter and the adjustment amount is automati-
cally updated. The procedure for adjusting the external
temperature signal is the same as that of the differential
pressure signal.
Manual adjustment
From the assigned temperature and the output of the
transmitter, calculate the amount of zero/span adjust-
ment manually and assign the calculated value to
parameters (CAL_EXT_TEMP_DEVIATION_LO and
CAL_EXT_TEMP_DEVIATION_HI).
Diagnosis of adjustment:
When the adjustment amount exceeds the following
adjustment ranges, “AL52: Out of external temperature
span adjustment amount range/AL52: Out of external
temperature zero adjustment amount range” generate an
alarm. The zero/span adjustment ranges are as follows:
(1) The ramp for the input/output of two adjustment
points must be within 10% of the ramp set
before shipment from the factory.
(2) The zero point adjustment amount must be
within
85ºC of the temperature set before
shipment from the factory.
