Siemens Automation and Drives has developed two telecontrol systems based on high-speed, low-cost GPRS (general packet radio services) data transmission.
The Sinaut Micro communication system for simple telecontrol tasks is based on the SimaticS7-200 micro controller as well as the GSM/GPRS MD720-3 modem and the Sinaut Micro SC OPC server.

With up to 256 controllers per server, several thousand remote stations can be connected to the central control station by radio. For the telecontrol of larger automation tasks with Simatic S7-300 and 400 controllers, the Sinaut MD740-1 is used – equipped with an Ethernet connection as well as a GPRS wireless modem, VPN (virtual private network) router and a firewall. Both new systems allow communication between the GPRS stations.

The new telecontrol systems are suitable for diverse wireless applications, ranging from mining, sewage plants, water treatment, oil and gas pipelines, pumping stations and traffic control systems, through to ‘intelligent’ advertising screens, lighthouses, ticket machines and ATMs and distributed energy generation and distribution in wind power, photovoltaic and district heating systems.

In previous systems, the central control room accessed remote stations using a GSM (global system for mobile communications) modem. To do so, the operator either had to set up an expensive dedicated line or use a point-to-point connection charged on a time basis and with the frequent disadvantage of longer connection build-up times. Compared with GSM, GPRS offers up to eight times the data transfer speed and also maintains the connection ‘online’, so the latest data can be transmitted to the central control on a permanent basis.

Costs are charged only in accordance with the transmitted data volume. This is significantly more cost-effective, particularly since mobile wireless vendors have been offering M2M (machine to machine) tariffs for approximately two years now, especially for automation and measured value acquisition. The costs are well below those of a standard telephone connection.

The Siemens system uses the VPN tunnel process as a technical trick for M2M communication, allowing central and remote stations to securely exchange data in both directions within the same network.

In conventional GPRS mobile phone applications, the mobile wireless operator prevents this in order to protect a mobile phone against, say, access from the internet. The Siemens system allows maintenance personnel, for example, who are at home but on call, to use the internet to carry out diagnoses via the control station with the remote stations connected via GPRS – and they can even intervene for control purposes.  o

For more information, visit www.siemens.com/sinaut