Home > Products > SMP > How does it work?

SMP Substation Gateway: Technical Overview

Request a demo | Request a quote | Download brochures

The SMP gateway is an advanced computing platform that implements all the functions required of a substation gateway—

• Protocol Converter—convert standard or proprietary device protocols to control center protocols.
• Data Concentrator—collect data from all connected devices, regardless of protocol, and make it available to control centers using LAN, WAN or serial connections.
• Terminal Server—provide a passthru communication mode to connect to substation devices for maintenance, monitoring and control.

Discover the SMP's advanced architecture and see how you can put it to work meeting your most challenging automation requirements—

Basic concepts

Introducing the SMP in the automation system

SMP Internals

The SMP as a protocol translator

The SMP as a data concentrator

Supporting multiple control centers

The SMP as a terminal server

Automation functions

Putting it all together

Basic Concepts

A typical automation system consists of a SCADA system, located in a control center, which is connected to devices such as RTUs, located in the substation. The SCADA regularly polls the devices in order to retrieve device readings and statuses. The operator uses the SCADA system to perform control functions on selected devices.

Since it is the control system that initiates data acquisition and control, it is considered to be the master system. Since the substation device responds to data acquisition and control requests, it is considered the slave system.

Introducing the SMP in the Automation System

When an SMP is introduced in the automation system, it has to act as both a slave and a master. The SCADA system interrogates the SMP as if it were a substation device. The SMP is thus a slave to the SCADA. However, since the SMP is connected to the substation devices, it must also be able to perform the functions of a master, such as polling for data and sending control requests.

SMP Internals

The SMP's internal architecture is based on a series of software components. Slave protocol components implement all the functions necessary to process requests received from a SCADA or control center. Master protocol components implement the functions necessary to poll devices and send control requests. Communication components provide the RS-232, RS-485 or TC/IP interfaces used by the protocol components to communicate with control centers and devices.

The master protocol component polls the device and stores the data that it retrieves in an internal database, called the Real-Time Data Exchange (RTDX). The RTDX is much more than a simple data store. Besides storing the current value of all the device data points, it also stores the different types of information than can be provided by a substation device, such as the quality and timestamp of the data. It also stores additional information such as device tags used for control functions, and event files.

The SMP as a Protocol Translator

The SMP architecture is flexible. To configure a protocol translator, you simply set up a master component using the device protocol and connection link. The SMP polls the device, retrieves the data and stores it in the RTDX. Then, you set up a slave component, using the control center protocol and connection link.

The SMP architecture ensures complete protocol and device independency. The SMP automatically provides the timestamp and quality attributes required by the slave protocol, even if it is not provided by the master protocol. The SMP automatically handles DNP3 and IEC 60870-5-101/104 control sequences, and performs the actions appropriate for the device.

The SMP as a Data Concentrator

The SMP simultaneously supports any number of master components. Each component has its own communications link and its own protocol. All the data retrieved from the devices is stored in the RTDX, where it becomes available to the SCADA. Using the SMP as a data concentrator is a simple matter of configuration, and it provides a highly efficient means of adding new devices to an existing automation system. The SCADA system has no knowledge of the new devices; it only sees new data points.

Supporting Multiple Control Centers

The SMP can also support any number of slave components. Each component has its own communications link, and all the device data can be sent to any number of SCADA and control centers, each with its own protocol. Sending data to a new control center is a simple matter of configuration.

The SMP as a Terminal Server

The passthru function provides direct access to any device connected to the SMP, for maintenance and engineering purposes. Connecting through the SMP provides an encrypted communications channel and ensures that only authorized personnel can modify device settings.

If the device supports it, the passthru function can even be used in interleaved mode, to connect to the device without interrupting SCADA data retrieval.

Automation Functions

Since it is connected between the substation devices and the control centers, the SMP is well positioned to implement advanced processing functions that would be impossible to perform in less sophisticated devices. The SMP provides the following automation capabilities—

• The Automation Functions module adds basic automation capabilities to the SMP – AND/OR inputs, best-of two inputs, set an output in a device according to the value of an input, inhibit a group of points, input latching, and more.
• The Soft PLC module and CoDeSys workbench provide a complete development environment for automation scripts using IEC 61131-3 languages. With the Soft PLC module, there is no need to add external PLCs to implement automation scripts, such as reclosers and load balancing.

Putting it all Together

With its advanced features, the SMP family of products provides all the functions you need to simplify the design of your substation automations system—

• 4, 8 or 16 Universal RS-232/422/485 serial ports
• Expandable up to 48 serial ports
• IRIG-B distribution on all serial ports
• Optional internal GPS Real-time clock
• Optional 16 port 10/100BaseTX, 10BaseFL, 100BaseFX Ethernet switch module

Note: Some features are not available on all models.

The SMP is provided with a complete set of Windows-based tools to simplify the design and commissioning of your substation automation system—

• Complete system and application logs, protocol and communication statistics and traces
• Built-in web server for real-time access to SMP data and operational status

With its secure VPN communications link and multi-level security model, the SMP provides a NERC-compliant solution to all your substation automation challenges.