Metro Istanbul

Commissioned by Istanbul Metropolitan Municipality, Siemens modernised the outdated underground train control system in Istanbul and replaced it by the integrated RailSCADA system Vicos RSC.
In order to ensure the communication between the new control system and existing substations and to integrate the new technology with available components and interfaces, IPCOMM has been instructed by Siemens to deliver and start up ipConvLite gateways, used for coupling substations with the new control station.

The communication between gateway and the superordinate control station SCADA is done via IEC 60870-5-104 protocol. The gateway is configured as "slave".
The communication between gateway and substations runs over Modbus protocol. Thereby the gateway is configured as "master".
As hardware platform our DIN-rail embedded controller HEC (without any rotating parts) is used. The HEC is equipped with a send and receive indicator for communication by default. The DIN-rail embedded controller has 4 RS232 interfaces; about 400 data points are transmitted per interface.
Distant terminals should be connected with the RS232 interfaces of the gateways by using V.24 standard.

A transmission of a time stamp is not supported by the Modbus protocol by default. Due to a proprietary enhancement of the original Modbus protocol, done by the supplier of the old system, it is possible to transmit indications with time tag. Because this modification is not documented, the challenge of this project for IPCOMM was to analyse the data traffic between the old control system and the substations.
The gateway time is synchronized over NTP time server. The connected stations are in turn synchronized by the gateways.