1.3
Technical Specifications
Daqu — Manual
E
– This is the same as B channel, but with stronger current generator. This
generator is used when the channel measures resistance in low resitance
range. The following currents are used to measure resistance. In all
cases, the voltage difference is limited to 0-5 V.
for 0–200 Ω range – 20 mA current,
for 0–400 Ω range – 10 mA current,
for 0–1000 Ω range – 5 mA current.
They are typically used to connect resistive fuel level sensors and this
solves many contact problems, which appear when A channel used for
the same purpose.
1.2.2
Digital Channels
The digital channels are used to measure time between pulses. Typical sensors
connected to digital channels are engine RPM, rotor RPM and fuel flow. There
are two types of digital channels used in Daqu.
Z
– is used to measure engine RPM. This channel has a special signal nor-
malizing circuit. Different engines have a very different signal levels. For
example, Rotax has up to 400 V (peak to peak) and Jabiru down to 1 V
(peak to peak). The circuit brings these different levels to a common
denominator. The circuit is able to process from 1.25 to 1000 pulses
per second. The upper limit equals to 20 pulses per revolution at 3000
PRM or 10 pulses at 6000 RPM. On lower end this equals to 75 RPM
at one pulse per revolution, 37.5 RPM at two pulses per revolution and
7.5 RPM at 10 pulses per revolution.
Y
– is used for signals with nicer shape and voltage level, like rotor RPM
sensors, fuel flow sensors, etc. Time between signals and sometimes duty
cycle is measured. The signal voltage can be in 0-30 V range. From 1.25
to 1000 pulses per second can be processed.
More details and examples of channel use are given in forthcoming chapters.
1.3
Technical Specifications
Table 1 lists technical specifications and figures 1 and 2 shows principal di-
mensions of Daqu.
©
Kanardia
2019
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