Communications
configuring
System- and communication configuring D7-SYS - SIMADYN D
3-53
Edition 12.2003
Normally, the transmit blocks are always enabled (SOK=1). If, due to time
fluctuations, the SYNPRO function block is calculated before SYNC has
expired (to the right in the diagram), the transmit data are not updated,
but the values from the previous sampling time are transferred. The
Synccycle and the data consistency are not influenced.
Instructions to achieve good SYNC functionality:
In addition to a low Synccycle, it is also necessary to have the lowest
amount of jitter (time-based fluctuations) in the Synccycle. The following
measures support this:
•
Irregular data transfer along the DP bus should be prevented: Single-
master operation; stations must not be temporarily switched-in.
•
Alarm tasks should not be configured on the same SIMADYN D CPU.
Sampling time overruns are not permissible; this would result in a
SYNC command failure or a shift by a complete sampling time.
•
Configure a high baud rate and short telegram lengths (the time to poll
a slave is included in the jitter.).
•
Configure the SYNPRO function block and all associated transmit
blocks in T1=T0 (basic sampling time). The SYNC command is always
initiated with the basic clock cycle interrupt. It is received with more
accuracy (timing accuracy) as an interrupt, initiated in the system
mode.
Configuring version 1 (3) is for generally less frequently used applications
of FREEZE:
•
Generating SYNC and FREEZE or only FREEZE commands.
•
The data consistency over all slaves is guaranteed.
•
The Synccycle is at least 300 % longer than the sampling time
(CNX>1).
−
the length of the transmit- or receive telegram (inputs or outputs)
may not exceed 32 bytes per slave.
−
all transmit- and receive blocks and the SYNPRO function blocks
must be configured in the same sampling time (on the same CPU).
−
the SYNPRO function block is configured as the last function block
in the processing sequence.
−
output SOK of function block SYNPRO should be connected with
the enable inputs of all (belonging to the slave group) transmit- and
receive blocks.
•
The bus circulating time must be less than the Synccycle minus 2 x
the sampling time. When the system is operational, it should be
checked whether the SOK output goes to “1“ once per Synccycle;
otherwise the Synccycle should be increased.
Configuring
version 3