Ad Signal Interface Requirements; Scaling Analogue Signals; Linear Transfer Characteristic (3-Point) - Danfoss pved-cl Operation Manual

Operation Manual
PVED-CL Controller for Electro-Hydraulic Steering, Version 1.38
Installation
Symbol
AD1_1000_Left
AD1_Neutral
AD1_1000_Right
AD1_Linear
AD2_1000_Left
AD2_Neutral
AD2_1000_Right
AD2_Linear
© Danfoss | May 2016

AD Signal Interface Requirements

When control signals are mapped to pin AD1 or AD2, the sampled voltage is range-checked to be
between 20 and 967 [AD full scale]. These bounds are used for detecting the signal being shortcut to
ground or VCC/battery power supply.
Voltage signals must always be in range in order not to trigger the signal validation monitor which results
in PVED fault state or reduced state. The maximum input range which leaves margin for noise etc. is 30 to
957 [AD full scale]. As a rule of thumb, one should attempt to have 0.5 V and 4.5 V at the end-stops and
approximately 2.5 V at neutral. The parameter defaults are set-up to this voltage range. A weak internal
pull-down resistor will pull the input below the fault detection threshold if the input is open-circuited.
The AD input impedance is > 1 MΩ.

Scaling Analogue Signals

The sampled analogue values needs to be scaled to the internal calculation domain before the signals
can be applied in the software control algorithms. Scaling is a method to fully utilize the software
calculation dynamic by assigning fixed calculation domain values to the equivalent analogue values for
maximum left, right and neutral and even intermediate values if desired. Scaling is done by sample value
to calculation domain transfer characteristics. Two different transfer characteristics are available for each
AD input.

Linear Transfer Characteristic (3-Point)

Linear transfer characteristic is suitable for sensors with a known characteristic such as joysticks and mini-
wheels. The transfer characteristic orientation depends on the sensor mounting orientation (both cases
are shown below).
AD1(2)_1000_Left
Max left = 800
Neutral = 440
Max right = 75
-1000
AD1(2)_1000_Left
Margin
Short-circuit
Index
65080
65086
65083
65087
65089
65095
65092
65096
•
When building a transfer characteristic, the characteristic shall be monotonically increasing or
decreasing. An attempt to build illegal characteristics is not possible.
•
AD values for Neutral shall be between the AD values for left and right.
Sampled AD value
Max left = 30
Neutral = 500
Max right = 957
AD1(2)_Neutral
0
Default
100
500
900
255
100
500
900
255
AD1(2)_1000_Right
1000
Scaled value
AD1(2)_1000_Right
Value range
[30;957]
0 (Non-linear), 255 (Linear)
[30;957]
0 (Non-linear), 255 (Linear)
11025583 | AQ00000216en-US0302 | 33