visiferm™ do sensors - Forbes Marshall

VISIFERM DO Operating Instructions
10. Testing and maintenance
Calibration
According to the standards, the sensor can be calibrated at air or in oxygenfree
environment (zero point). This is very rarely necessary in the most
applications. If there are already displacements of measuring values of only
few percents within few days, then a damage of the luminophore due to
measuring medium and cleaning medium has to be expected. In this case it
has to be considered whether a more frequent exchange of the sensor cap
can be accepted or whether another measuring principle e.g. with a classical
OXYFERM sensor should be used!
HINT: The sensor needs a preheating time of 10-15 minutes after switching
on. In this phase measurements are already possible. However, for an optimal
calibration you should wait this time.
Calibration in Modbus or 4-20 mA mode
The calibration of the sensor in the 4-20 mA mode only is possible via Modbus
RTU. Therefore, most easily VISICAL or the VisiConfigurator freeware with
the USB-RS-485 Modbus converter can be used (see chapter ‘Configuration
of the sensors‘ and ‘Accessories‘). The operation of the accessories is shown
by the specific instructions.
During the calibration the sensor independently examines the correctness and
stability of the oxygen signal.
Calibration in ECS mode
The calibration in ECS mode takes place like in classical sensors in the
measuring device at which the sensor is connected. For this, consult the
operation instructions of the measuring device!
HINT: The concept of VISIFERM DO sensors enables the calibration of all
used sensors in the lab with a VISICAL module or with a personal computer or
laptop via Modbus and then a direct use at classical measuring devices
without a new calibration at the measuring device. This is possible, since with
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