4.4 Latching
4-13
Feed Axis
Operation
4.4
Latching
The latch function saves the position of the machine when a latch signal is input while there is a latch request.
Latch operations are required to determine the position for a machine operation, such as homing for a feed
axis, setting the orientation of a spindle axis, or setting the reference point for threading with a lathe. The skip
function is used to automatically measure workpieces and tools. When the skip function is used, the position is
saved by specifying a latch signal selection. Then, all remaining movement is cancelled and the next step is
executed.
The SERVOPACK contains functions to perform these latch operations, and they can be used together with
the INTERPOLATE (34 hex) command for axis movement.
Use the SVCMD_CTRL bit field in the INTERPOLATE (34 hex) command for latch requests and latch signal
selection.
Touch probes or other such equipment use one of the external input signals 1 through 3 of SERVOPACK
external input signals (CN1). Select the external input signal that has been connected.
4.4.1
SVCMD_CTRL Bit Field (Latch Operations)
Note: Refer to
7.2.5 I/O Signals
in the
Σ
-V-SD Series User’s Manual
(Manual No.: SIEP S800000 78) for details on exter-
nal input signals.
4.4.2
SVCMD_STAT Bit Field (Latch Operations)
The following SVCMD_STAT.L_CMP1 and SVCMD_STAT.L_CMP2 bits indicate the completion of a latch
operation.
Bit 8
LT_REQ1
Latch Request 1
0
None
Rising edge
1
Request for latch
Description: Requests a latch through phase C or an external input signal.
Bit 9
LT_REQ2
Latch Request 2
0
None
Rising edge
1
Request for latch
Description: Requests a latch through phase C or an external input signal.
Bits 10 and
11
LT_SEL1
Latch Signal Selection 1
0
Phase C
Rising edge
1
External input signal 1
2
External input signal 2
3
External input signal 3
Description: Selects phase C of LT_REQ1 or an external input signal. Set this bit to a different value
than LT_SEL2.
If LT_SEL1 is changed while LT_REQ1 is 1, the LT_SEL1 selection for when LT_REQ1
is 1 will be continued.
Bits 12 and
13
LT_SEL2
Latch Signal Selection 2
0
Phase C
Rising edge
1
External input signal 1
2
External input signal 2
3
External input signal 3
Description: Selects phase C of LT_REQ2 or an external input signal. Set this bit to a different value
than LT_SEL1.
If LT_SEL2 is changed while LT_REQ2 is 1, the LT_SEL2 selection for when LT_REQ2
is 1 will be continued.
Bit 8
L_CMP1
Latch Completion 1
0
Latch is not completed.
1
Latch is completed.
Description: This status is used to determine the completion of a latch operation for LT_REQ1. L_CMP1
remains 1 until LT_REQ1 changes to 0.
Bit 9
L_CMP2
Latch Completion 2
0
Latch is not completed.
1
Latch is completed.
Description: This status is used to determine the completion of a latch operation for LT_REQ2. L_CMP2
remains 1 until LT_REQ2 changes to 0.
