Operating instructions

Functions, monitoring, and protective functions
9.4 Extended functions
Drive converter cabinet units
384 Operating Instructions, 10/2008, A5E00288214A
Note
The velocity override is effective during the search for the cam. By changing the encoder
data set, status signal r2684.11 (reference point set) is reset.
The cam switch must be able to delivery both a rising and a falling edge.
During the reference point approach when evaluating the sensor zero mark, the 0/1 edge
is evaluated with increasing actual position values and the 1/0 edge with falling actual
position values. Inversion of the edge evaluation is not possible at the sensor zero mark.
If the length measuring system has several zero marks which repeat at cyclic intervals
(e.g. incremental, rotary measuring system), you must ensure that the cam is adjusted so
that the same zero mark is always evaluated.
The following factors may impact on the characteristics of the "reference cam" control
signal:
• Switching accuracy and time delay of reference cam switch
• Position controller cycle of drive
• Interpolation cycle of drive
• Temperature sensitivity of machine’s mechanical system
● Reference point approach, step 2: Synchronization to reference zero mark (encoder zero
mark or external zero mark)
Reference cam available (p2607 = 1):
In step 2, the drive accelerates to the velocity specified in p2608 (zero mark approach
velocity) in the direction opposite to that specified by binector input p2604 (reference
point approach start direction). The zero mark is expected at distance p2609 (max.
distance to zero mark). The search for the zero mark is active (status bit r2684.0 = "1"
(reference point approach active)) as soon as the drive leaves the cam (p2612 = "0") and
is within the tolerance band for evaluation (p2609 - p2610). If the position of the zero
mark is known (encoder evaluation), the actual position of the drive can be synchronized
using the zero mark.
The drive starts the reference point approach (see step 3). The distance traveled
between the cam end and zero mark is displayed in parameter r2680 (difference between
cam and zero mark).
Encoder zero mark (p0495 = 0), no reference mark present (p2607 = 0):
Synchronization to the reference zero mark begins as soon as the signal at binector input
p2595 (start referencing) is detected. The drive accelerates to the velocity specified in
parameter p2608 (zero mark approach velocity) in the direction specified by the signal of
the binector input p2604 (reference point approach start direction).
The drive synchronizes to the first zero mark. and then starts to travel towards the
reference point (see step 3).