34 OI/266CXX/266JXX/HART-EN Rev. B | 266CRx, 266JRx, 266CSx, 266JSx
10.3.1 Setting precalibrated devices
(The lower range value has already been set to 0.)
266Cxx transmitters do not support this function if the "Level
measurement" calculation function has been activated. In this
case, the correction must be made using the optional LCD
indicator, the handheld terminal, or the DTM.
IMPORTANT (NOTICE)
For this purpose, the DIP switch on the
electronics board must be set to position 1.
A PV Bia
s / Offset correction can be performed via the local
push buttons as follows:
— Separate the transmitter from the process and equalize
the pressure in the two measuring chambers by adjusting
the bypass valve in the manifold.
— Check the transmitter output signal
If it is at 4 mA (or PV = 0), zero point correction is not
required.
If the output is not at zero, proceed as follows:
— Unscrew the screws attaching the name plate to the top
of the transmitter housing
— Rotate the name plate so that the push buttons can be
accessed
— Check that the write protection rotary switch is set to write
enable
— Press and hold down the zero button (Z) on the top of the
transmitter for at least 3 seconds
The output signal switches to 4 mA and the message
“OPER DONE” appears on the LCD display (if there is
one).
— If nothing happens, check the write protection rotary
switch.
It is probably set to write protection.
— For all other diagnosis notices, refer to the instructions
— As soon as zero point correction is complete, reconnect
the transmitter to the process
— Open the pressure equalization valve on the manifold.
— Open the shut-off valve of high-pressure side
— Open the pressure equalization valve on the manifold.
— Open the shut-off valve on the low-pressure side
10.3.2 Zero
-point increase/suppression on precalibrated
devices
(e.g., 4 ... 20 mA = -100 ... 100 mbar)
This function is only supported by 266Jxx and 266Cxx
transmitters if the calculation function has been disabled.
IMPORTANT (NOTICE)
F
or this purpose, the DIP switch on the
electronics board must be set to position 0.
—
Isolate the transmitter from the process and vent the
transmitter measuring chamber(s) to atmosphere
— Apply the lower range value pressure (4 mA).
The pressure must be stable and applied with a high level
of accuracy (< 0.05 %, observing the set damping value)
— Check the transmitter output signal
If it is at 4 mA (or PV = 0), zero point correction of the
transmitter is not required.
If the output is not at zero, proceed as follows:
— Unscrew the screws attaching the name plate to the top
of the transmitter housing
— Rotate the name plate so that the push buttons can be
accessed
— Check that the write protection rotary switch is set to write
enable.
— Press and hold down the zero button (Z) on the top of the
transmitter for at least 3 seconds
The output signal switches to 4 mA and the message
“OPER DONE” appears on the LCD display (if there is one)
— If nothing happens, check the write protection rotary
switch.
It is probably set to write protection.
— For all other diagnosis notices, refer to the instructions
— As soon as zero point correction is complete, reconnect
the transmitter to the process
— Open the pressure equalization valve on the manifold.
— Open the shut-off valve of high-pressure side
— Open the pressure equalization valve on the manifold.
— Open the shut-off valve on the low-pressure side
IMPORTANT (NOTICE)
Afte
r the transmitter has been adjusted as
described above, the zero bias / offset value is
activated and stored in the memory of the
transmitter. In this case calibration of the
transmitter is can no longer be executed. Only if
the PV bias / offset value is reset, will a sensor
calibration be possible again.
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