Siemens 3VF Series Communications Manual page 29

Communication System Manual
In order to guarantee optimum data transfer times, the large volume of 3WN6 input and output data is
divided into two transfer modes on PROFIBUS-DP: cyclic and acyclic transfer modes:
1
8 bytes of acyclic data
Fig. 4: 12-byte I/O channel for 3WN6
1. Cyclic data traffic: cyclic data (e.g. actual maximum phase current I
information which is transferred at regular intervals. Important information from the circuit-breaker is
automatically transferred from the DP/3WN6 interface to the I/O area of the bus master in this way.
Similarly all the important (cyclic) data contained in the I/O area of the bus master are also
transferred to the circuit-breaker.
Cyclic 3WN6 input data include, for example, the setting current value for overload releases (setting
current I ), as well as the circuit-breaker remote ON/OFF command. Cyclic output data from 3WN6
r
include the switching state of the circuit-breaker (ON/OFF), the 3WN6 ready-to-close signal, as well
as various group signals (group fault signal, group warning signal, group error signal) which can
indicate whether a fault (e.g. trip due to overload), a warning (e.g. current warning) or a processor
error is present.
2. Acyclic data traffic: Acyclic data are only transferred from the interface to the bus master or from
the bus master to the circuit-breaker when a request is transmitted. This means that specific
messages are sent from the bus master to the 3WN circuit-breaker when required.
Acyclic data from 3WN6 (i.e. data which are requested given certain conditions) include, for
example, the position state of the circuit-breaker (e.g. test or connected for draw-out circuit-
breaker). In order to determine the cause of a group signal, for example, (see above), the actual
cause is determined by means of an acyclic message. In the case of a group fault, for example, it is
possible to determine whether the cause is due to a "g" release (earth fault), a "z" release (delayed
short-circuit), an "n" release (instantaneous short-circuit), or whether there was another cause for the
release.
Acyclic data written to 3WN6 include, for example, the setting values for "z" release, "n" release or
current phase imbalance. When used in conjunction with a communication module with
measurement functions (Z=F05), additional setting values can be written, e.g. undervoltage release,
overvoltage release or load shedding signals.
The message list in section 3.4, page 37 describes in detail the functionality of the various overcurrent
releases on PROFIBUS-DP. This will allow the user to select the required overcurrent release together with
the correct communication module (Z=F01) or communication module with measurement functions
(Z=F05). In addition, the message list contains the information required for handling the acyclic data traffic
in the bus master.
Table 3, page 30 lists a number of standard versions of communication-capable 3WN6 circuit-breakers (3-
pole) and their order numbers. The table can be used to look up the most economical solution for obtaining
the required bus functions. Ordering details for the hardware and software which is required in addition to
the circuit-breaker can be found in section 3.1.2, page 26.
Note: The recommended versions are based on standard applications using 3-pole circuit-breakers. Please
refer to the catalog "Products and Systems for Non-Fused Energy Distribution (NS PS)" for further details.
Version 1.0 (05/98)
8
© Copyright Siemens AG 1998. All rights reserved.
3WN6 Circuit-Breakers
9
4 bytes of cyclic data
) correspond to basic
Lmax
12
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