SplitOPC software product, developed by «Prosoft-Systems» company is a routing communication OPC server, intended for organizing system of guaranteed data collection and transmission, telecontrol commands transmission in OPC format through the distributed (physically and structurally) networks.

Purpose of use

One of the main advantages of SplitOPC is the high productivity and reliability while working with large data volumes through the low-quality channels. Besides, SplitOPC has a set of unique features, making possible connection geographically and adiministratively distributed systems, making data collection and management in real-time scale.

Main features

  • «End-to-end» data communication, irrespective of the place of joints in various segments of the local/global network, with consideration of the installed firewalls.
  • Definition and creation of a new data access route, in case the old one is broken (dynamic rerouting). A new (backup) route is found automatically, if connection through the running route has been lost. When the shortest data communication link is recovered, the route should be automatically rearranged to cut down overhead expenses.
  • «Hot» reservation with automatic catch-up of the role, in case the mainstream server breaks down (server duplication is required).
  • Cryptographic protection of any segments of internet traffic with an arbitrary long key.

Support of global alias tables of OPC tags allows to create an alias for signals, already existing in the system, which makes it easier to attach available Automated Control Systems and processing equipment to information network, and reduces as much as possible the number of man-hours, spent for porting.

The system of signal naming, that allows giving a unique name to each signal, is constructed similarly to the Domain Name Structure (DNS), permitting to precisely determine, which level data should be attributed to. On figure 1 is the structure of water temperature signal name for the station 23, located near Nice (France), requested by the operator in Munich through the central ABC server in New York.

High rate of transmitting big number of tags (up to 200 000) in real-time operation mode, use of unique shrinking algorithms, allowing to transmit required data volumes through low-rate communication links (Table 1).

Table 1

Speed of communication
channel (Kbit/sec)

Quantity of transmitted, every
second changing signals
(no encryption)

Quantity of transmitted, every
second changing signals
(with encryption)

Estimated (for real automation
objects) quantity of
transmitted signals
(no encryption)

Nondedicated lines

1200

12

6

52

4800

32

15

140

9600

85

38

340

19200

204

91

860

33600

530

252

2100

Dedicated lines

~ 2 Mbit

~ 8 000

~ 3 500

~ 30 000

~ 10 Mbit

~ 60 000

~ 28 000

~ 120 000

~ 100 Mbit

~ 85 000

~ 40 000

~ 200 000

 

For evaluating the throughput of non-dedicated line connection were used Zyxel and GSM Siemens TC35i modems. In the last column are the values, calculated on the base of the proportion of frequently/rarely-changing signals, taking place in real conditions at the industrial automation objects.

  • The guaranteed time for the telecontrol transmission is achieved by means of the integrated priority system, provided that executive instructions are of the highest priority.
  • Definition of rights (reading, recording) for the access to certain groups of signals prevents from unauthorized instructions or change of values.

The 100ms delay time on the picture, includes the delay in transmission of the command at the intermediate node – time needed for elaborating the command and transfer IP -> OPC -> IP. In case of sufficient channel throughput and guaranteed low time of the batch passing through the channel/network infrastructure, this value could be used as a coefficient for estimation of time required for telemechanic command transfer. For using this condition in real projects, to calculate the delay this coefficient (100 ms) has to be multiplied by the number of intermediate nodes.

If the time of batch transmission is not guaranteed, in case of Internet transmission, we need to take into consideration the time, lost for transmission of the batch and possible delays in communication equipment and make the certain corrections for each case.

On Figure 2 is depicted the channel Paris – Nice (2 Mbit) for which the correction value is ~800 ms, that gives in total a one second delay for telemechanics command transmission.

Adding gateways into the real-time systems (for example, QNX – «Telemechanics» on base of Moscad controllers) enables transmission of the telecontrol commands and data collection in OPC format without significant time and financial costs. The values, received from such kind of systems, become available in form of OPC tags to which could be written data for transmitting telecontrol commands.

With bidirectional gateway-convertor OPC <-> IEC 60870-5-104 we have the possibility of integrating data and telemechanic commands, received in this format and convert the data from one format to another in real time. Use of these solutions enables «transparent» integration of heterogenous fragments into a common system. For the current day SplitOPC with different gateways is one of the basic elements of dispatching control systems at AK «Transneft», OAO «Lukoil», OAO «Rosneft», OAO «Sibneft», OAO «Tatneft».

While creating the data collection system we integrate many OPC servers from different developers and suppliers of technologic equipment.

Example of the system created in AK «Transneft»

“Prosoft-Systems” is an active member of OPC Foundation (www.opcfoundation.org) since 2004, all our software is tested for compliance to OPC DA specifications (OPC Compliance tests).

Система Orphus