DESIGNER’S HANDBOOK 4189350049C EN
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5.6.9.7 Single high voltage input
AX1: +HV1 (High voltage 1) on terminal 11, +HV2 on terminal 7 or +HV3/Dim on terminal 2. All 3 with 0V reference
at AGND, terminal 1.
The high voltage input can be configured to use full data resolution within the ranges:
+/-7.5 V, +/-15 V or +/-30 V, this secures a very high accuracy in the analogue measurements.
The input is pre-configured to an input range that is scaled to an absolute data range for the selected data type.
All voltage inputs are measured with a resolution in mV (1V = 1000mV)
Example:
A rudder indicator with voltage input, +/- 10 V input is scaled to +/-45.0
o
rudder angel.
In this case 3-point input calibration is typically used and this means that:
i/o-pair 1: -10 000mV = -450 (=-45.0° (PS)),
i/o-pair 2: 0mV = 0° and
i/o-pair 3: 10 000mV = 450 (+45.0° (SB))
Input load:
The high input resistance (112kΩ) of this input results in an insignificant load of the voltage source. The internal
resistance of the power source and resistance in the signal wires should be as low as possible. If the total source
resistance exceeds 1
00 Ω, adjustment of the input voltage pre-set may be necessary.
Potentiometer used as input source is covered in a separate section.
5.6.9.8 Single high current input
AX1 current loop inputs:
+HI1 (High current 1) on terminal 9, -HI1 on terminal 8 or
+HI2 on terminal 5, -HI2 on terminal 4.
The high current input can be configured to use an input range between /-10 mA or +/-20 mA.
The internal current resolution is in µA (1mA = 1000µA)
Very often this input type will be pre-configured to 4 to 20 mA. (4000 to 20000 µA)
The high current input is overcurrent-protected by an auto recovery fuse (polyfuse). This adds slightly to the input
resistance, but has no impact on the measuring accuracy.
The internal resistance is between 55 and 65 Ω, resulting in a max. voltage drop of +/-1.3 V at +/-20 mA. The total
voltage drop must be considered when several current inputs are serial-connected. In the application note for 4 to
20 mA rudder indicator systems, you will find a detailed description of how to design a current loop system.
5.6.9.9 Single low current and low voltage input
AX1 current loop inputs:
+LIV1 (Low Current/Voltage 1) on terminal 9, -LI1 on terminal 10 or
+LIV2 on terminal 5, -LI2 on terminal 6.
The low current input can be configured in the range: +/-2 mA (+/-2000 µA).
The same input is also used as a low voltage input and can be configured in the range +/-2 V (+/-2000mV).
Please note that the input resistance is only 1 kΩ. This input is designed to withstand accidental connection to the
24 V supply voltage, at least for a short period of time.
5.6.9.10
Input lost detection on a current input
The 4 to 20 mA is still one of the most popular input types for indicators and in XDi it is possible to insert an input
current lost and an over current limit that will flag a AX1 input lost message in case of a wire break or if the supply
voltage for the sensor is lost.
In our standard indicators with 4-20mA input we normally set the low current level to 3500µA (3.5mA) and the over
current level to 21000 µA (21 mA).
