Interfaces 6
miriac EK-5744 User Manual
V 1.2
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© MicroSys Electronics GmbH 2017
6.7 Analog Inputs
The SBC features four analog current sink inputs. Each channel is connected to
two redundant input circuitries and two redundant analog channels of the MPC-
5744P. The analog circuitry of each input can be stimulated to detect system faults.
For detecting open or shorted sensor lines, the analog ports use the current mode,
which also makes cable lengths uncritical. The complete input range covers 0mA to
24mA, however the valid range uses only 4mA to 20mA. If a value is detected out-
side the valid range, the sensor and/or the cabling might be faulty.
A valid measurement of the input current is only possible if no stimuli of the input
circuitry are active, i.e. the test signals HAIN0# to HAIN7# as well as LAIN# must
all be at a logical high.
The range of 0-20mA at the connector is translated to an analog voltage of 0V to
2.9V at the MPC5744P port pin according to the following table.
XAINx
HAINx#
LAIN#
AINx
Range
0mA
high
high
0.00V
invalid
1mA
high
high
0.14V
invalid
2mA
high
high
0.29V
invalid
3mA
high
high
0.43V
invalid
4mA
high
high
0.58V
valid
5mA
high
high
0.72V
valid
6mA
high
high
0.87V
valid
7mA
high
high
1.01V
valid
8mA
high
high
1.16V
valid
9mA
high
high
1.30V
valid
10mA
high
high
1.45V
valid
11mA
high
high
1.59V
valid
12mA
high
high
1.74V
valid
13mA
high
high
1.88V
valid
14mA
high
high
2.03V
valid
15mA
high
high
2.17V
valid
16mA
high
high
2.32V
valid
17mA
high
high
2.46V
valid
18mA
high
high
2.61V
valid
19mA
high
high
2.75V
valid
20mA
high
high
2.90V
valid
21mA
high
high
3.04V
invalid
22mA
high
high
3.19V
invalid
23mA
high
high
3.33V
invalid
24mA
high
high
3.48V
invalid
Table 6-16: Analog Input 4-20mA Input Validity
