Supervisory & Control Engineering, a leading automation and process control and telemetry solutions company, now offers third layer DNP-3 communication protocol in its ScadaPack PLC/Telemetry controllers.
DNP-3
DNP-3 (distributed network protocol) is a standards-based communications protocol developed to achieve interoperability among utility systems. It is a robust, flexible, non-proprietary protocol with functionality that includes: addressing for over 65 000 devices on a single link; time synchronisation and time-stamped events; broadcast messages; data link and application layer confirmation. As a standards-based, open protocol, DNP-3 is managed by an international user group. The protocol has a rich set of functions and was designed to work well in a wide area network. DNP-3 uses an object-based application layer and supports multiple operating modes including: poll-response, polled report-by-exception, unsolicited response and peer-to-peer. Users choose DNP-3 if polled or changed/recovered data is at risk due to prolonged communication outages.
Applications are prevalent in the power, oil and gas, water/wastewater and security industries worldwide and the product is rapidly gaining acceptance and aspiration in the water/wastewater, environmental monitoring and mining industries in South Africa.
Product distinction
It is their ability to reliably communicate through radios, telephone lines, satellites, or virtually any communication media that distinguishes scada and telemetry applications from traditional factory automation. No other aspect is more technically challenging. It is also the ability to deal with communications issues that distinguishes the ScadaPack PLC/RTU from a factory automation PLC.
ScadaPack communication ports can be used with any type of leased-line or dialup modem, radio transceiver, spread-spectrum radio, cellular transceivers or communication link to another device. All ports can be used with custom protocols or the built-in Modbus driver, and all ports can be used to program and diagnose the unit. Each port can have a unique Modbus station number, up to 65 000 addresses are supported, and can use either the RTU or ASCII version of Modbus, with any combination of baud rate, parity, duplex and word length. All ports support RTS/CTS handshaking for radio transmitter control, and all ports can be used for Modbus Master and/or Slave operation enabling special functions such as report-by-exception.
For maximum versatility, the ScadaPack provides store-and-forward capability, which allows Modbus messages to be received and retransmitted to other slaves. Store-and-forward is especially useful with radio telemetry systems, because it can eliminate the need for repeaters. The ScadaPack itself acts as a repeater. Any scada software package that supports Modbus, Modbus TCP, DNP-3 or A-B DF1 protocols is compatible with ScadaPack controllers. If a custom protocol is required, it can easily be implemented using TelePACE C tools. The ScadaPack can communicate with virtually any serial device.
Added value: Ethernet transmitters
The 4102MMT Modbus Multivariable Transmitter offers precise measurement of process pressure, differential pressure and temperature. As a fully digital transmitter, the product offers a built-in choice of Modbus protocol over serial and/or Ethernet communications, along with an optional PID controller and analog output. With this choice, the 4102MMT can be used in a wide variety of installations including low power transmitters in remote locations or as an addressed device offering control and measurement in an extended Ethernet network. The unit can be calibrated from a remote ScadaPack controller using RealFLO software.
For more information contact Carlo Shields, Supervisory and Control Engineering, 012 653 1027, [email protected]
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