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1 Introduction
This document describes how to connect the IEC870-5-103 compliant communications interface to a control system or
interrogating computer.
To access the interface the user will need appropriate software within the control system or on the interrogating
computer (e.g. Reydisp Evolution).
2 Connection specification and relay settings
This section defines the connection medium as defined by IEC 870-5-103. Appendix A shows some typical
communication connections.
2.1. Recommended cable
Selection of fibre optic cable is critical. Fibres should be terminated with 9mm SMA connectors.
The recommended type is 200μm Plastic Coated Silica (PCS). This will allow a maximum transmission
distance of 100m between Argus relays. It will also be the maximum distance between the ring network
and the fibre to RS232 converter.
Alternatively, 1mm polymer cable may be used to reduce cost. This will provide transmission distances
of up to 43m between relays. Note that the distance from the transmit output of the RS232 / fibre optic
converter to the receive input of the first Argus relay should be not more than 6m. The distance from
the transmit output of the last Argus to the receive input of the converter may be upto 43m.
No other types of cable are suitable for use with Argus relays.
2.2. Connection Method
Argus relays can be connected in either a Star or Ring fibre-optic communications network. If star
connected then a passive fibre optic hub must be used. A lower cost option is the ring configuration
where the Argus relays are 'daisy chained.' That is, the transmit output of the first relay is connected to
the receive input of the second relay, and so on until the ring is complete.
Communication to the ring may be achieved either locally in the substation or remotely via the Public
Switched Telephone Network (PSTN). If remote communication is desired, then additional modem
equipment must be installed.
Reydisp Evolution is a PC based software package providing capability for both local and remote
communication. It provides features such as download of disturbance and event records, upload of
relay settings, real-time monitoring of measurands and remote control of plant.
2.3. Transmission Method
The transmission method is Half Duplex serial asynchronous transmission. In IEC 870-5-103 the line
idle state is defined as Light ON. This can alternatively be selected as Light OFF in the
Communications Interface menu of the relay if required for use with alternate hardware (See Section
2.5).
2.4. Transmission Rate
Rates of 19200, 9600, 4800, 2400, 1200, 600, 300, 150, 110 and 75 bits per second (BPS) are
provided. Only 19200 and 9600 BPS are standard in IEC 870-5-103, the additional rates are provided
for local or modem communications.
2.5. Line Idle Setting
The line idle setting can be set to be either ON or OFF and the setting must be compatible with the
device connected to the relay. The IEC 870-5-103 standard defines a line idle state of Light On. If the
device the relay is connected to does not have a compatible fibre-optic port then a suitable electrical to
optical converter is required to connect it to a standard RS232C electrical interface. A suitable
converter is the Sigma 4 type, which is available from Reyrolle Protection.
©2010 Siemens Protection Devices Limited
7SG11 Argus 8 Communication Interface
Chapter 4 Page 3 of 8
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