09.95 10 Axis and Spindle Installation
10.5.3 Positioning mode, M19, M19 through several revolutions
Accuracy
• The position is entered with an accuracy of 0.01
o
. The positioning accuracy achieved by
the spindle depends on a number of factors:
– The resolution of the angle measuring system
– The gain factor of the active gear ratio
– The drift
– The interfacing to the drive system.
Restrictions
• Gear ratio changing cannot be employed in the positioning mode.
• M19 must not be activated or programmed when the G96 function is active.
Selecting the positioning mode
A distinction must be made between absolute positioning (M19 from NC or PLC) and
incremental positioning (M19 through several revolutions from the command channel).
Positioning mode can be selected by NC, PLC or command channel. The following functions
are available:
PLC: Request for M19
• IS:POSITION SPINDLE
– set position from MD 452*
CC: Request for M19tsr
• ”Incremental spindle positioning” function
– set incremental traversing path in user data of command channel
– spindle override remains active
NC: Request for M19
• M19 in part program or during overstore
– set position as S value
– set position from setting data (SD 402*) if no S value has been programmed.
Acknowledging M19
If the signal "Spindle position reached" (DB 31 DL k bit 4) is output during positioning by the
NC, the PLC must then output the signal "Acknowledge M19" (DB 31 DR k + 2 bit 2) if
function M19 is to be terminated. However, signal "Acknowledge M19" must not be output
until the spindle has settled in position. If serious overshoot occurs (gain factor very large) , it
is advisable to delay output of signal "Acknowledge M19" to the NC until signal "Spindle
position reached" has been pending for a machine-specific time tv.
Signal "Acknowledge M19" not only cancels spindle positioning but it also stops the spindle
(like M05) so that a new M03 or M04 has to be programmed in the part program to enable the
spindle to accelerate to the S value previously programmed.
Signal "Acknowledge M19" is only active in combination with "PLC spindle control".
© Siemens AG 1992 All Rights Reserved 6FC5197- AA50 10–55
SINUMERIK 840C (IA)
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