Velocity Edge GX440 User's Guide download pdf (Page 290)

ALEOS 4.3.4 Software Configuration User Guide

290 4114514

Supervisory Control and Data Acquisition (SCADA)

Supervisory Control and Data Acquisition (SCADA) describes solutions across a

large variety of industries and is used in industrial and engineering applications to

monitor and control distributed systems from a master location. SCADA

encompasses multiple RTUs, a central control room with a host computer (or

network), and some sort of communication infrastructure.

SCADA allows for “supervisory” control of remote devices as well as acquiring

data from the remote locations. Programmable Logic Controllers allow for a

higher degree of automated SCADA.

Programmable Logic Controller (PLC)

A Programmable Logic Controller (PLC) is a small industrial computer which

generally monitors several connected sensor inputs and controls attached

devices (motor starters, solenoids, pilot lights/displays, speed drives, valves, etc.)

according to a user-created program stored in its memory. Containing inputs and

outputs similar to an RTU, PLCs are frequently used for typical relay control,

sophisticated motion control, process control, Distributed Control System and

complex networking.

Modbus TCP/IP

Modbus TCP/IP simply takes the Modbus instruction set and wraps TCP/IP

around it. Since TCP/IP is the communications standard for the Internet and most

networked computers, this provides a simpler installation. Modbus TCP/IP uses

standard Ethernet equipment.

Modbus on UDP

When Sierra Wireless AirLink devices are used in place of radios, a AirLink device

is connected to the central station (host) and an AirLink device is connected to

each remote unit. When the AirLink device is configured for Modbus with UDP, the

AirLink device connected to the host can store a list of IP addresses or names

with matching IDs. When the host at the central station sends serial data as a poll

request, the AirLink device at the host matches the RTU ID to a corresponding IP

of a AirLink device at a remote unit. A UDP packet is assembled encapsulating

the RTU ID and serial data transmitted from the host. The UDP packet is then

transmitted to the specific AirLink device at the remote unit matching the RTU ID.

The remote AirLink device then disassembles the packet before transmitting the

RTU ID and serial data to the remote unit. The remote units operate in normal

UDP mode and their data is sent to the host via the remote AirLink device and

host AirLink device.

1 2 ... 285 286 287 288 289 290 291 292 293 294 295 ... 411 412

No comments

Velocity Edge GX440 User's Guide Page 290