8. Connecting the transducers
necessary be programmed with several measuring ranges or scaling settings;
and two or three sensors, if pin assignment so permits, can be combined in a
single connector (e.g. rH / NTC, mV / V, mA / V, etc.). The additional measur-
ing channel numbers per connector go up in steps of 10 (e.g. the first sensor
has channels M0, M10, M20, M30).
Double connectors with 2x differential voltage / differential current
cannot be used with this device.
On the measuring instrument this gives the following channel assignment :
8.3 Potential separation
When organizing a properly functioning measuring setup it is very important to
ensure that no equalizing current can flow between sensors, power supply, and
peripherals. All points must therefore lie at the same potential and / or any un-
equal potentials must be electrically isolated.
Sensors combined within one connector and sensors with their own power
supply are electrically interconnected and must therefore be operated in isola-
tion. The voltage at the measuring inputs themselves must not exceed 5 volts
(between B, C, D, A and - ).
The power supply is isolated by the transformer in the mains adapter or by a
DC/DC converter (OA2450-U or ZA2690-UK). Data and trigger cables are
equipped with optocouplers. Where analog output cables are not electrically
isolated the recording device or the sensors must be zero-potential.
16 ALMEMO
®
2450-1
M0
00
10
20
30
1. chan.
2. chan.
3. chan.
4. chan.
A2
A1
DC
sensor channels
P0
M0
data cable
AC
DC
DC
DC
ADC
uC
U-
U+
Sensor
Power supply
10..30V=
230V≈
