4.2 Measuring Inputs and Additional Channels
Either the ALMEMO
®
socket M (9) or the clamping connector (8) can be used
as measuring input for the ALMEMO
®
4490-2. When using the clamping
connector only one measuring channel is available and must be programmed
via the instrument. When an ALMEMO
®
sensor is connected to socket M the
programming can cover up to four measuring channels (M0 to M3) and will be
automatically loaded from the connector.
The additional channels can be
especially used for humidity sensors with 4 measuring variables
(temperature/humidity/dew point/mixture ratio) or for function channels. A
sensor can, if required, also be programmed with several ranges or scalings
or, depending on the pin assignment, 2 or 3 sensors can be combined in one
connector (e.g. rH/Ntc, mV/V, mA/V etc.).
The measuring input, outputs and power supply are electrically
isolated from each other and a potential difference of 50V at
maximum is permissible between them. However, sensors
combined within one connector and sensors with an own
power supply are electrically connected to each other and
must, therefore, be operated in isolation. The voltage applied
to the measuring inputs must not exceed
±
5V (between B,C,D
and A or - respectively).
As only
one
input but
two
options for a connection are
available, an ALMEMO
®
connector and a sensor with a
clamping connector must not be plugged in at the same time!
The cold junction compensation for thermocouple measurement is integrated
in socket M of the device. Therefore, thermocouples should always be
connected with an ALMEMO
®
connector.
0
1
2
3
chann.1
chann.2
chann.3
chann.4
M
A2 A1
4490-2
ALMEMO
4490-2
13
Connection of the Transducers
