Network Topology; Settings; Iec Class Ii Measurands; Iec Class Ii Update Period - Siemens 7SG11 Manual

4.2.4

Network Topology

Communication networks can be connected either in star or ring format.
Laptop computer
4.2.5

Settings

Communication parameters of Communications Interface:Comms Baud Rate, Communications Interface:Comms Parity and
Communications Interface: Line Idle should match those of the communicating device.
4.2.6

IEC Class II Measurands

Class II measurands can be sent as either ASDU 3 (reports 1 current channel) or ASDU 9 (reports 9 channels, Ia,
Ib, Ic, Va, Vb, Vc, P, Q), The values are returned as a fraction of a nominal value ie 1A, 63.5v. The Communications
Interface:IEC Class II Measurand setting should be set as appropriate for each system.
4.2.7

IEC Class II Update period

The class II measurand is updated in the relay at a period dependant on the Communications Interface:Class 2 Update
Period setting. This ranges from instantaneous (constantly updated) to every 60s (updated every minute).
4.2.8

IEC Class II scaling

The measurands returned are fractions of nominal system quantities. The maximum range of the measurand can
be set either 1.2 or 2.4 times the nominal. Values that exceed this range will be returned as the maximum value
and flagged overflow. Note using 2.4 times scaling will double the range but half the resolution per bit. The
Communications Interface: IEC Class II Scaling setting should be set as appropriate for each system.
4.2.9

Baud Rate

Rates of 19200, 9600, 4800, 2400, 1200, 600, 300, 150, 110 and 75 bits per second are provided. However, only 19200
and 9600 are defined in IEC 60870-5-103, the additional rates are provided for local or modem communications.
The Communications Interface:Comms Baud Rate setting should match that of the communicating device, e.g. P.C.

4.2.10 Comms Parity

IEC 60870-5-103 defines transmission as using Even parity, however, in some instances an alternative may be
required. The Communications Interface:Comms Parity setting allows parity of None to be selected. This setting should
match that of the communicating device, e.g. PC.

4.2.11 Relay Address

Each relay on a network must have a unique address, between 1 and 254, as set by the Communications
Interface:Relay Address setting. A relay with the default address of 0 will not be able to communicate.

4.2.12 Line Idle

The IEC60870-5-103 protocol defines a line idle state of Light On. Binary '0' is represented by light on, binary '1' is
represented by light off, and when a device is not communicating it idles with the light on (sending '0'). This allows
detection of a broken fibre condition. When the line is idling, a binary '0' should be received constantly. If binary '1'
is received constantly, then no light is being received, hence the fibre may be broken.
The Communications Interface: Line Idle setting must be set to be either on or off to be compatible with the
communicating device connected to the relay.
©2013 Siemens Protection Devices Limited
Tx
Sigma 4
(SG4-103)
Rx
Figure 4.2-1
7SG11 Argus Technical Reference
Rx
Tx
P300007 Communications.vsd / Sigma 4 remote
P20007 Page 65 of 71