Signal Processing; Evaluating Acoustic Channels - Siemens 7MJ2000-1A 00 Series Operating Instructions Manual

Signal processing

7.1

Evaluating acoustic channels

Introduction
Essentially, the four sensor inputs are evaluated according to the same principle, with the
only differences being in the signal names and/or the associated parameters. If a channel is
disconnected due to its configuration (P.1, P.2, P.3 or P.4 set to "oFF"), the measured value
is set to "0" and no alarm is generated.
The evaluation takes place in two steps:
1. Calculation of the measured value as shown in the "Block diagram for calculation of the
2. Formation of the alarm messages as shown in "Block diagram for the formation of alarm
Step 1: Calculation of the measured value
In accordance with the "Block diagram for calculation of the measured value" figure, the
electrical signals from the sensors are amplified, filtered and converted into a digital signal by
an analog-to-digital converter. The sensors are simultaneously checked for cable failure. The
level is calculated from the signal and then filtered and further processed to a measured
value. The amplification can be set in two steps for each measurement channel with the
(P.1, P.2, P.3, P.4). The upper limit frequency of the filter is determined with parameter P.40.
Parameter P.39 can be used to adjust the algorithm to various pump designs. Depending on
the parameter (P.1, P.2, P.3, P.4), the sound level to be output as the measured value is
determined separately for each measurement channel:
● A simulated value in simulation mode.
● The maximum value in test mode.
● The difference between maximum and minimum level in normal measurement mode.
SITRANS DA400 for oscillating positive displacement pumps
Operating Instructions, 09/2008, A5E00841120-03
measured value" figure.
messages" figure.
7
63