AVL AVL DiCom 4000, Service Manual

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4000 Evaluation Unit
Service Manual 4-5
4.2 Hardware Setup
4.2.1 Main Board
The main board represents the heart of the electronics and uses predominantly SMD
technology. The most important function blocks are described below.
4.2.1.1 Digital System
The digital system is built around the highly integrated Intel I80C196NT controller with
20 MHz clock frequency.
The program memory is a flash eprom with 0.5 MB (16 bit bus, 0 wait states, several
independent program and parameter blocks) and can therefore be reprogrammed in the
field.
Two static RAMs are used to store data with a total of 256 KB (16 bit access, 0 wait states).
A further 256 K area of the address space is used as a page area for the internal expansion
memory (on a module receptacle) and the external memory card. The slot for the memory
card is welded to the main board.
The address coding is by programmable logic.
The RTC (real-time clock) has a ten-year function guarantee on the lithium cell.
The main board (and therefore the evaluation unit) is unambiguously identified by a
silicone serial number which carries an individual 48-bit code. The internal temperature
of the instrument is monitored by an NTC.
4.2.1.2 Analogue Data Acquisition
The necessary analogue values are measured by the 10-bit ADC installed in the 196NT.
The values measured are the opacity signal, various temperatures, analogue channels
from the speed/angle board and from the free slot and various values for self-diagnostic
purposes (supply voltages, valve motor current). Where necessary, the data is reprocessed
digitally (in particular linearisation, demodulation, digital filtering). This allows, for
example, the filter parameters for the opacity signal to be adjusted to the various
directives.
4.2.1.3 Remote Control Receiver
An integrated receiver/pre-amplifier is connected to the main board by a short cable. The
output signals are conditioned by the 196NT via an EPA channel.