Functions of the ALMEMO 809
Scaling
The corrected measured value on each measuring channel can also be further
scaled in terms of zero-point and gain based on the base value and factor. The
decimal point position can be set by means of the 'Exponent' function. Scaling
values can be calculated automatically by setting to zero and entering the no-
minal setpoint.
Limit values and alarm
Per measuring channel two limit values can be set (one maximum and one mi-
nimum). In the event of one of these limit values being infringed relay output
modules actuate the associated alarm contacts; these can be allocated indivi-
dually to specific limit values. Hysteresis is set by default to 10 digits; however,
this can be adjusted to any value between 0 and 99 digits. A limit value infrin-
gement can also be used to automatically start or stop measured value recor-
ding or via macros to control device functions in any way required.
Sensor locking
All sensor data stored in the EEPROM in the plug can be protected - by means
of a graduated locking function - against undesired access.
5.1.2 Measuring operation
For nine V6 sensors up to 36 measuring channels are available; i.e. it is thus
also possible to evaluate double sensors, individually scaled sensors, and sen-
sors with function channels. All activated V6 measuring channels are conti-
nuously scanned at a rate of 10 MOPS (measuring operations per second).
When there are numerous measuring points to consider, the overall response
time can be shortened by increasing the measuring rate up to 100 MOPS. A
D7 sensor has up to 10 channels and a sampling rate corresponding to its own
individual measuring speed.
Measured values
Measured values are acquired automatically with auto-zero and self-calibrati-
on; however, they can also be corrected and scaled individually 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
To achieve optimal measured value acquisition some sensors require certain
special measuring functions. Cold junction compensation is provided for ther-
mocouples; temperature compensation is provided for dynamic pressure, pH,
and conductivity probes; and atmospheric pressure compensation is provided
for humidity, dynamic pressure, and O2 sensors.
ALMEMO
®
809
11
