7SG15 MicroTAPP Communications Interface
1 Introduction
The MicroTAPP relay has provision for communication either locally to a computer or remotely to an operations
centre.
The Communication Interface, Figure 1, incorporates the following ports:
• A pair of fibre optic ST connectors for transmit and receive communications to a substation SCADA or integrated
control system (Com 1).
• A pair of fibre optic ST connectors for access by protection engineers (Com 2). The same port can be accessed
instead through an RS232 connector mounted on the relay fascia and provides facilities for access to the relay
from a laptop computer or PC.
IRIG-B
Com 1
Tx
Rx
Tx
Rx
Com 2
Case Rear
Figure 1
The IEC60870-5-103 standard protocol used by the relay for the transfer of data is fully described in the Reyrolle
document 434TM05 “Informative Communication Interface”. An IRIG-B port is also provided for time
synchronisation.
The Sigma range of products is available to connect to the fibre optic ports of the relays.
Sigma 1 is a fibre optic hub with one system port and up to 29 ports for connecting to the relays.
Sigma 3 is a fibre optic to dual RS232 interface. It has one fibre optic port for connection to the relay(s), and two
electrical RS232 ports. The rear electrical port is intended for connection to a control system. The front port allows
local access, for example, from a laptop PC. When a device is connected to the front port the rear is overridden,
see Figure 2.
Sigma 4 is a portable fibre optic to RS232 conversion unit.
2 Connections
2.1 Physical Characteristics
The modular II relays are equipped with two fibre-optic, and one electrical serial communication ports. The fibre
optic ports named Com1 and Com2 are located at the rear of the relay. Each consists of a pair of ST connectors,
a transmitter (Tx) and a receiver (Rx). See Figure 1 left.
The RS232 electrical port is on the front of the relay. It uses a 25 pin D type socket. The relay is wired as a Data
Communications Equipment (DCE) device, allowing standard serial cables to be used for connection to a
computer. The electrical port is also named Com 2, allowing local access overriding the fibre-optic Com2.
©2011 Siemens Protection Devices Limited
Chapter 4 Page 3 of 8