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22) WHEEL ANGLE
Angle measurement degrees. For the configuration with toggle switches only, it
is the steered wheel angle in the range 0
±
180 degrees. WHEEL ANGLE is zero
in the position where an edge is detected in the straight ahead toggle switch.
23) SLOPE PEAK
This reading is just for debugging the maximum slope of the potentiometers
connected to the eps-ac0. Especially when a reduced sensor equipment is
chosen (just a single command potentiometer or just a single feedback
potentiometer without encoder), a concern regarding the safety raises: if a
single potentiometer fails a sudden movement of the steered wheel may occur
with danger. To avoid this problem it is necessary to detect any failure in a
single potentiometer. This is hard to do because the failure mode can be quite
different. Anyway, the best countermeasure we can take, is to seek for the wiper
voltage changes faster than its physical limit. In fact, for the limited speed of the
steering motor (or of the steering wheel), the slope in the wiper voltage must be
limited under a certain threshold. When this slope threshold is overtook, the
potentiometer may be assumed broken. So, it is useful to measure the
maximum slope occurring in your application when right working, in order a right
slope threshold can be chosen to avoid an alarm occurs when the potentiometer
is not failed (see 12.4.6.3).
The SLOPE PEAK reading in the tester menu is a real time measurement of the
slope peak of the potentiometers. In particular:
When the special adjustments DEBUG OUTPUT is other than Level 12 or 13,
SLOPE PEAK supplies the slope peak of the CPOC1 set point potentiometer
(CNA#9).
When the special adjustments DEBUG OUTPUT is Level 13, SLOPE PEAK
supplies the slope peak of the CPOT feedback potentiometer (CNB#6).
When the special adjustments DEBUG OUTPUT is Level 12, SLOPE PEAK
supplies the slope peak of the CPOC2 set point potentiometer (CNA#8).
The SLOPE PEAK measurement is the difference between two AD conversions
of the selected potentiometer picked up with 16 msec long interval. The SLOPE
PEAK reading can be converted in a Voltage change (
∆
V in volts) of the wiper
voltage in an interval 16 msec long, with the formula:
∆
V = SLOPE PEAK*5/1024 = Voltage change in Volts in 16 msec
(e.g. When SLOPE PEAK is 61 it means the selected potentiometer, in the
worst case, changes 61*5/1024=0.3 V in 16 msec.).
Obviously the SLOPE PEAK reading must be compared with the threshold for
the STEER SENSOR KO and JERKING FB POT alarms (see 14.1.3.6-7). The
STEER SENSOR KO alarm may be adjusted (see MAX SP SLOPE 12.4.6.3);
the JERKING FB POT occurs when the CPOT slope, overtakes a constant
threshold is
±
0.3 V in 16 msec (i.e. SLOPE PEAK=
±
61).
24) READ FBPT AT SW1
This reading is used only when the FEEDBACK DEVICE is OPTION #3
(FBENC, FBPOT, SW1). It gives the FB POT value at the initial matching with
the falling edge on the straight ahead switch (SW1). This reading is expected to
reply the SET FBPOT AT SW1 value (see 12.4.2.18 in the adjustments menu).
When a displacement exists between these two readings, a POSITION ERROR
alarm may occur (see 14.1.3.5).
25) TRUCK SPEED
Percentage value. It represents the truck speed represented in percentage of