Siemens SIMADYN D Manual page 141

Communications configuring
Configuring
version 2
1
Input SOK
0
Sampling time
Synczyklus
SYNC_command
Bus circulating
time
Fig. 3-16 Timing diagram, SYNC version 2
3-52
When initiating the SYNC command, the transmit blocks are inhibited
(SOK=0) for two sampling times (one bus circulating time). The transmit
blocks are enabled in the third sampling time after initiating the SYNC
command (SOK=1).
Configuring version 2 has the highest SYNC performance:
• Generating SYNC commands.
• The data consistency over all slaves is guaranteed.
• Synccycle=sampling time (CNX=1)
− the length of the transmit telegrams (outputs) for each slave may
not be greater than 32 bytes.
− all transmit blocks and the SYNPRO function block must be
configured in the same sampling time.
− high baud rate (>1.5 Mbaud). For lower baud rates, the time
conditions can hardly be maintained.
− the bus circulating time may only be a maximum of 50 % of the
sampling time.
− the bus circulating time must also be so low, that one sampling
time expires from the start up to the calculation of the function
block SYNPRO. This cannot be guaranteed, but must be checked
when the system is operational.
Example:
• Synccycle=sampling time
• Bus circulating time=0,3 x sampling time
• Assumption: The SYNPRO function block calculates at the center of
the sampling time (before all transmit blocks)
FB-SYNPRO
SYNC_quit
(FB-SYNPRO is calculating too early)
FB-SYNPRO
SYNC_quit
SYNC_command
System- and communication configuring D7-SYS - SIMADYN D
SYNC_command
Edition 12.2003