01/2007
8.3 Creating a PROFIBUS configuration
8-189
© Siemens AG 2007 All Rights Reserved
SINUMERIK 840Di sl Manual (HBIsl) – 01/2007 Edition
Via parameter: Master Application Cycle T
MAPC
defines the integer ration be-
tween the master application (NC position controller) and the isochronous DP
cycle.
Using ratios other then 1:1, the dead times of the position controller can be re-
duced if NC hardware of the lower performance range is used.
Notice
On a DP slave S120 used with SINUMERIK 840Di sl, the ratio between the
master application cycle T
MAC
and DP cycle time T
DP
must be 1:1.
Master application cycle = DP cycle
Tab: Clock synchronization
Master application cycle [msec]:
Factor: 1
Via parameter: Actual–value acquisition Ti defines the time at which the actual
value (actual position value) can be read in from a DP slave S120.
Note
You are strongly recommended to use the same value for the time of actual
value acquisition Ti for all DP slaves S120, in particular if the axes interpolate.
Notice
The following condition must be observed for the time of actual–value sensing
T
I
:
DP cycle >= actual value acquisition >= base time
Tab: Clock synchronization
Actual value acquisition [ms]:
Factor: Factor
Via parameter: Setpoint acceptance To defines the time when the speed set-
point of the NC position controller is accepted by a DP slave S120.
Note
You are strongly recommended to use the same value for the time of setpoint
acceptance To for all DP slaves S120, in particular if the axes interpolate.
Master application
cycle T
MAPC
Dialog box:
Continuation
Actual value
acquisition
Ti
Dialog box:
Continuation
Setpoint
acceptance
To
8 PROFIBUS DP Communication
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