Daqu — Manual
3.4
Resistive Sensors on E Channels
A
A
11
12
A
A
A
8
9
10
A
7
11
12
10
6
7
8
9
5
3
4
1
2
+
-
EGT
1
EGT
2
EGT
3
EGT
4
AUX
3
AUX
4
+
-
+
-
+
-
+
-
+
-
R
R
Engine
block
Engine GND
splitter
Figure 4:
One wire resistive sensor principle. The
invisible
ground wire is
routed via engine block, represented by the dashed line.
3.3.2
Two Wire Sensors
Two wire resistive sensors (also known as sensors with isolated return) have
two wires. One wire connects to positive terminal of A channel and the other
to the negative terminal. As A channels are isolated too, they are floating by
default. This means that negative terminal requires some reference. Typically,
any Daqu GND pin can be used for the reference. Figure 6 gives an example
where two such sensors are connected.
3.4
Resistive Sensors on E Channels
Resistive fuel level sensors that are submerged in fuel may have problems
when connected to the A channel. They may be losing contact. Namely,
A channel uses pretty weak measuring current, and consequently a very small
voltage difference to measure the resistance.
E channel is designed to apply larger measuring current, and consequently
also larger voltage difference for the same resistance. This reduces contact
problems with sensors submerged in fuel. Thus a fuel level resistive sensor
shall be connected to an E channel whenever this is possible. The current and
voltage are still low enough to be safe. Figure 7 illustrates such connection.
Additional wire to reference ground is not needed with E channel. See also
section 1.2.1 for more details.
15
©
Kanardia
2019
