Siemens SITRANS DA400 Operating Instructions Manual page 18

Description
3.4 Mode of operation
By using a bridge rectifier, the current from a suitable external feed splitter creates the
internal current voltage of 3.3 V and 8.2 V for circuit 2. The supplementary voltage U
obtained from the PROFIBUS-PA signal of an external coupler. Circuits 1 and 2 have split
potential regarding the current and each other. Circuit 1 consists of a microcontroller (µC2)
that is responsible for PROFIBUS communications. It is connected to the micro-controller
(µC1) in circuit 2 via a serial, split potential coupler. At the heart of this circuit is a signal
processor with integrated analog-digital converter for high-speed recording and evaluation of
the available signals. Moreover, an EEPROM safe from a voltage drop is activated for
storing data and the display, and the key strokes are read in.
The six digital outputs are separated individually by potential and designed for connection to
a NAMUR connection hardener. The maximum four acoustic sensors are connected to the
four-pole "Sens1" to "Sens4" blocks. In each case, two terminals provide the supply for the
sensor electronics and two terminals are used to connect the sensor signal.
Different standard signals can be connected at each of the four universal inputs "In 1" to
"In 4". The switching of the four terminals is to be set up according to signal or sensor type
(0/4 to 20 mA, digital signal for 24 V, closing contact).
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SITRANS DA400 for oscillating positive displacement pumps with protection against explosion
Operating Instructions, 10/2007, A5E00841127-01
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