5
5.8
Motion Control with PROFIBUS–DP (from SW 3.1)
5-298
Siemens AG 2005 All Rights Reserved
SIMODRIVE 611 universal Description of Functions (FBU) – 04.05 Edition
The clock–cycle synchronous PROFIBUS ensures that the IPO clock
cycles run in synchronism in all of the axes involved which means that
the traversing enable signals are effective at precisely the same time.
The SYNC telegram from the DP master guarantees that the axes start
in the same DP clock cycle.
Dx
Dx
Dx
GC
MSG
RES
MSG
Dx
Dx
Dx
MSG
Dx
Dx
Dx
MSG
Interpolation
clock cycle (IPO
clock cycle)
Slaves 1 to 3
Master
T
I
T
O
T
MAPC
= T
DP
T
I
RES
GC
RES
GC
T
I
T
DX
PLC user
program
IPO
IPO
IPO
IPO
IPO
IPO
IPO
IPO
IPO
IPO
IPO
IPO
IPO
IPO
IPO
T
MAPC
Master Application Cycle Master application clock cycle
T
DP
DP cycle time DP cycle time
T
DX
Data Exchange Time: Sum of the data transfer times of all of the slaves
T
I
Input time: Instant in time for the actual value sensing
T
O
Output time: Time of setpoint transfer
GC
Global Control Telegram (Broadcast Telegram)
Dx
Slaves: Net data transfer between master and slave 1 – n
MSG
Acyclical utilities (for example, DP/V1, token passing)
RES
Reserve: ”Active pause” until the isochronous (equidistant) cycle has expired
Fig. 5-28 Example: T
IPO
= 4 ms and T
DP
= 8 ms
Timing
5 Communications via PROFIBUS DP
08.99