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4. Introduction
bration; (see 11).
Scaling
The corrected measured value on each measuring channel can also be further
scaled in terms of zero-point and gain - using the base value and factor. The
decimal point position can be set by means of the exponent function. The scal-
ing values can be calculated automatically by setting to zero and entering the
nominal setpoint.
Limit values and alarm
Per measuring channel two limit values can be set (1 maximum and 1 mini-
mum). In the event of one of these limit values being exceeded relay output
modules actuate the associated alarm contacts; these can be allocated indi-
vidually to specific limit values. Hysteresis is set by default to 10 digits but this
can be adjusted to any number between 0 and 99. The exceeding of a limit
value can also be used to start or stop measured value recording automatical-
ly.
Sensor locking
All sensor data stored in the connector EEPROM can be protected by means
of a graduated locking function against undesired access.
4.1.2 Measuring operations
For each transducer up to four measuring channels are available; i.e. it is also
possible to evaluate double sensors, individually scaled sensors, and sensors
with function channels. All activated measuring points are continuously
scanned at a rate of 2.5 measuring operations per second. The selected
measuring point (M0) has preferred status, i.e. is rescanned each 2nd time
(semi-continuous mode). The data is output via the interface and, if available,
to an analog output. To shorten the response time when there are many
measuring points this rate can be set to continuous and increased up to maxi-
mum 100 measuring operations per second.
Measured values
Measured values are acquired automatically with auto-zero and self-
calibration; however, they can also be freely corrected and scaled as required.
With most sensors a sensor breakage is detected automatically.
Analog output and scaling
Each measuring point can be scaled, by means of analog start and analog
end, in such a way that the measuring range thus defined covers the full range
of the analog output (2 V, 10 V, or 20 mA). At the analog output the device can
output the measured value from any measuring point or a programmed value.
Measuring functions
With some sensors, to achieve optimal measured value acquisition, certain
special measuring functions are required. Cold junction compensation is pro-
vided for thermocouples; temperature compensation is provided for dynamic
pressure, pH, and conductivity probes; and atmospheric pressure compensa-
10
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