Types Of Communication - Siemens Sinamics S120 Function Manual

Two solutions are possible for the electrical isolation:
● Using an isolating transformer for each slave infeed train. The primary side of the
● Using a three-winding transformer for the master and slave infeeds. In this case, only the
Whichever solution is chosen, it must be noted that a separate transformer must be used for
each Active Line Module (slaves 1 to 3).
DC breaker
Note
When an infeed develops a fault it is disconnected on the line side by the line contactor, on
the DC link side, using a DC breaker. Infeeds must not be switched in to a charged DC link.
The DC link must be discharged before another infeed train can be switched in.
An infeed may only be connected to a charged DC link if a DC breaker with pre-charging
branch is installed.
7.9.3

Types of communication

To implement master/slave operation, the CUs must be able to communicate with one
another. The master passes the active current setpoint to the slaves. To optimize V
(DC link voltage), the dead times during communication must be kept to a minimum.
PROFIBUS slave-to-slave communication
The data is exchanged directly between the CUs without passing via the DP master. A
PROFIBUS master (higher-level controller) is required to act as a "clock generator" (e.g. an
S7-CPU). The minimum PROFIBUS cycle time that can be set depends on the Profibus
master specifications.
Isochronous mode must be set for PROFIBUS. The PROFIBUS cycle time must not exceed
2 ms otherwise the closed-loop control may start to oscillate.
In order to ensure that other infeeds do not switch to fault status when one CU fails, the fault
message F01946 "Link to Publisher disconnected" must be deactivated.
The number "1946" can be set in one of the parameters p2101[0..19] and p2101[x] set to "0"
in order to block fault message F01946. This means that the drive will not shut down when
one slave-to-slave communication node fails.
In a master/slave infeed, a common current controller cycle is essential, particularly when
infeeds with different outputs are used. If the number of PROFIBUS nodes or drives
increases, this can affect the bus cycle or current controller sampling time.
Drive functions
Function Manual, (FH1), 01/2012, 6SL3097-4AB00-0BP2
transformer is to be connected to the grounded or ungrounded line transformer. The
secondary side must never be grounded.
neutral point of one winding may be grounded to prevent further electrical coupling via
ground.
Function modules
7.9 Master/slave for Active Infeed
control
dc
393