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Local Database
- Referred to in this manual this means a database held on your own PC.
MODBUS
- Modbus
is an industry standard protocol used in many SCADA packages for net-
work control. The recorders can be inserted into existing networks using Modbus or linked
directly to a controller over an RS485 link. Modbus TCP/IP is available through the Ethernet inter-
face.
MODBUS X
- Modbus X differs from the standard Modbus only by the 4 byte floating point order
being reversed for application compatibility.
Network
- Two or more computers connected together by cable so that they can exchange infor-
mation and resources. A network may be made up of computers, printers, scanners, or other
devices.
Network drive
- A drive that resides somewhere in the network rather than on your own com-
puter.
Network interface card (NIC)
- An adaptor card that lets the computer attach to a network
cable.
Network server
- A computer that stores and manages programmes, data and peripherals such
as output devices for other computers and workstations connected through the network. Also
called a file server.
OPC client
-
OLE Process Control
. A software application that can be used to interface realtime
data via the comms server.
Packets
- Data is sent over a network in manageable chunks called packets or frames. The size
and makeup of a packet is determined by the protocol used.
Parity
- This ensures data is transmitted accurately and transfers correctly. The parity bit is
added to every data unit (typically 7 or 8 bits) that are transmitted. The parity is set to either odd
or even. Both the transmitting and receiving device must be set up the same.
Passive hub
- A passive hub serves simply as a conduit for the data, enabling it to go from one
device (or segment) to another.
Peer-to-peer network
- A network in which any computer can be a server. A scheme in which
networks computers share resources; each work station may either be client or server. See also
Dedicated network.
PPP
-
Point to Point Protocol
. This is an Internet protocol (IP) which packages the computers
TCP/IP packets and forwards them to the Server. From the Server they can actually be put on the
Internet. PPP has error detection and is preferred over SLIP.
Profibus
- Profibus allows communication between devices of different manufacturers without
any special interface adjustment. Profibus can be used for both high-speed time critical applica-
tions and complex communication tasks.
Protocol
- The rules of the network game, governing the transfer of data between a computer
and peripherals. Protocols define standardisation formats for data packets, techniques for detect-
ing and correcting errors.
Realtime data
- Logging or graphing realtime data means that the software and the recorder
have been synchronised in time to communicate the transfer of actual current ‘happening now’
data.