Zapi EPS-AC0 SWs&ENC User Manual page 18

4.5.2.1 Straight ahead toggle switch
The straight ahead toggle switch must be of NPN type (i.e. it must connect a minus
battery to CNA#3).
A possible arrangement for the straight-ahead switch (proximity switch) is shown in
Figure 4-4- below. The proximity switch is connected to the truck frame; the Iron
plate rotates together with the steered wheel.
It is handled this way:
4) At key-on, the eps-ac0 turns the steering motor moving in either CW or CCW
side, according to whether the output level from the straight ahead switch is high
or low (in the above sketch a proximity sensor is used as a straight ahead
switch).
5) When the falling edge on the prox switch is detected, the encoder counting is
initialized to 0 and the steered wheel is centered.
6) Then the encoder counting is continuously updated to measure the steered
wheel angle.
At key on, the Iron plate (with the shape shown in the sketch), provides the correct
direction in which the eps-ac0 must turn the steering motor in order the falling edge
on the proximity switch is detected.
Together with the straight-ahead switch, a second toggle switch could be adopted to
detect when the steered wheel is in the 90 degrees limiting position. This second
toggle switch must be connected to CNA#2 and GND (minus battery).
An hardware setting AUX FUNCTION 11 (see 11.4.5.5) is used to specify the toggle
switches configuration (one or two toggle switches and their succession during
time).
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Figure 4-4
Figure 4-5
AEMZP0EA - EPS-AC0 SWs&ENC - User Manual