Feature Configuration
ANCA Motion
DS619-0-00-0019 - Rev 0
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DCH is managed through various settings of the f
ollowing IDN’s:
IDN
Label
S-0-0041 / 41
Homing Speed
– to Home Switch
S-0-0042 / 42
Homing Max Acceleration
S-0-0052 / 52
Reference Distance 1
S-0-0054 / 54
Reference Distance 2
S-0-0147 / 147
Homing Parameter
S-0-0148 / 148
Drive Controlled Homing Procedure Command
S-0-0150 / 150
Reference Offset 1
S-0-0151 / 151
Reference Offset 2
S-0-0403 / 403
Position Feedback Value Status
P-0-0432 / 33200
Extended Homing Parameter
P-0-0437 / 33205
Homing Speed
– to Index Pulse
P-0-0438 / 33206
Homing Runoff Distance
P-0-0439 / 33207
Drive Controlled Homing Procedure Command Acknowledge
The DCH function is configured and executed by the following steps, and is illustrated in terms of logic levels in
Figure 10-11:
1. The DCH uses two numbers to relate an axis home position relative to a machine zero position.
a.
The ‘reference distance’ describes what may be considered the “best” sensor estimate for
a valid home position for the drive’s associated machine axis. In order to find this distance
the axis is driven to one of its limits of allowed motion, often a probe/proximity sensor that
is called the “home switch It is then reversed away from this limit until it detects an index
pulse coming from its associated encoder (usually from the motor encoder, but not
always). This position is now set internally as the reference distance, and its value is
made available for each end of an axis as 1 and 2 through the IDN’s S-0-0052/52 and S-0-
0054/54.
b. It is sometimes u
seful for a machine that is being ‘homed’ to travel a further fixed distance
away from the above ‘reference distance’ in order to finally be considered as at home
position. This
is called the ‘reference offset’, and can be set for each end of an axis as 1
and 2 by configuring the value of the IDN’s S-0-0150/150 or S-0-0151/151.
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These parameters may need to be re-commissioned (i.e. Changed) whenever the motor or encoder
setup has changed.
Warning:
Care must be exercised so that all homing related IDN’s are suitably configured whenever
hardware (e.g. motor or encoder) changes are made, since unexpected behaviour may result.
2. Start the DCH higher level function execution by setting the DCH procedure command IDN S-0-
0148/148 to a value of 3.
3. The axis will then move to the home switch, following a velocity profile that uses a programmed
homing speed (S-0-0041/41) and de-/acceleration (S-0-0042/42). The direction in which to home is
set via IDN S-0-0147, and the particular bit settings are specified in the accompanying document
“Digital Servo Drive SoE Parameter Reference” (dd_reference_SoE_parameter.pdf)
4. The axis will then move off the home switch by a distance defined by the homing runoff distance (P-
0-0438/33206), note the sign of this runoff distance (+/-) affects the direction the axis travels when it
moves off the home switch.
5. Once at the runoff distance, the axis will then commence to move at home speed (to index pulse)
(P-0-0437/33205) in the direction specified by the sign of this speed, until an index pulse is
registered from the associated encoder.
If homing off the home switch (not index pulse), this step is
skipped.
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This ‘reference offset’ does NOT currently get used by the AMD2000, it may do so in future releases.
