06.03
10.6 Digital and analog I/O devices
10-383
Siemens AG, 2003. All rights reserved
SINUMERIK 840Di Manual (HBI) – 06.03 Edition
10.6.5
Time behavior
After the system variables have been set, e.g. $A_OUT[8] for setting the 8th
digital output of the NC on a SIMATIC-S7 signal module connected on PROFI-
BUS DP, the system variable is transferred from DP master to the signal module
along PROFIBUS DP during the next position controller cycle.
The signal module will then provide the signal to the appropriate with the output
next output cycle. The PROFIBUS DP cycle and the cycle of the signal mod-
ule are not synchronized during this process.
The transmission cycle described is illustrated in Fig. 10-34, page 10-383.
The time properties when reading in a digital or analog input are analogously to
the properties described above.
Dx
Dx
Dx
GC
MSG
RES
MSG
R
R
DP slave:
Signal module
NC:
Position controller
and interpolator
T
M
T
MAPC
T
DP
RES
GC
PROFIBUS DP
communication
2
R
Dx
Dx
Dx
1
T
DX
3
R
R
R
R
Pos
.
R
Interpol.
Fig. 10-34 Time behavior when outputting an output signal with optimized DP cycle
Explanations regarding Fig. 10-34:
T
MAPC
Master application cycle: NC position controller cycle
With SINUMERIK 840Di, the following applies in all cases: T
MAPC
= T
DP
T
DP
DP cycle time: DP cycle time
T
DX
Data exchange time: Total of transfer times of all
DP slaves
T
M
Master time: Shift of starting time of the NC
position control
GC
Global Control: Broadcast message frame for cyclic
synchronization of the isosynchronism between DP master
and DP slaves
10 NC Start-Up with HMI Advanced
