Measuring Operations - Ahlborn ALMEMO 2490-2 Operating Instructions Manual

5. Introduction
via its screw terminals. For digital input signals, frequencies, and pulses, ad-
apter connectors are available with an integrated microcontroller. It is thus pos-
®
sible to connect virtually any sensor to any ALMEMO measuring instrument
and to change sensors without the need for any extra settings.
Function channels
Maximum, minimum, average, and differential values from certain measuring
points can be programmed as function channels, also internal channels, and
can be processed and printed out like normal measuring points.
Units
The 2-character units display can be adapted for each measuring channel so
that both the display and the printout always indicate the correct units, e.g.
when a transmitter is connected. Conversion between °C (Centigrade) and °F
(Fahrenheit) is performed automatically.
Measured value designation
Each sensor is identified by means of a 10-character alphanumeric name. This
name is entered via the interface and will appear in the printout or on the com-
puter display.
Correction of measured values
The measured value on each measuring channel can be corrected both in
terms of zero-point and gain; this means that even sensors usually requiring
initial adjustment (e.g. expansion, force, pH) can be freely interchanged. Zero-
point correction and, partly at least, gain adjustment can be performed at the
touch of a button. Sensors with multi-point calibration can also be connected;
(see Manual Section 6.3.13).
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.
Limit values and alarm
Per measuring channel two limit values can be set (1 maximum and 1 minim-
um). In the event of one of these limit values being exceeded relay output mod-
ules actuate the associated alarm contacts; these can be allocated individually
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 automatically.
Sensor locking
All sensor data stored in the connector EEPROM can be protected by means
of a graduated locking function against undesired access.

5.1.2 Measuring operations

For each transducer up to 4 measuring channels are available; i.e. it is also
possible to evaluate double sensors, individually scaled sensors, and sensors
with function channels. You can move forwards or backwards from one meas-
10 ALMEMO 2490
®