User`s manual

Watlow Controls Communications Guide 27
Protocol
A set of rules for communication. This
will specify what method to transfer
information, packet size, information
headers and who should talk when. It is
used to coordinate communication
activity.
Receive
To accept data sent from another device.
The device that receives the data is the
receiver.
Register
An area of memory that provides
temporary storage of digital data.
RJ11
A connector used on most telephones that
has four terminals.
SDS
Smart Distributed System is a CAN based
device-level control network that can be
scan or event driven, configured as master-
slave or peer-to-peer, and can support
devices of varying complexity. . Uses
twisted pair wires for the power and bus.
Slave
A device that only responds to commands.
This device never starts communication
on it’s own. Only the Master can do this.
(See Master)
SCADA
Supervisory Control and Data Acquisition
Serial
To process something in order. First item,
second item, etc.
Serial Communications
A method of transmitting information
between devices by sending all bits serially
(see serial) over a single communication
channel.
EIA/TIA-232
(Formerly RS-232) -
An Electronic Industries Association
(EIA)/Telecommunication Industry
Association (TIA) standard for interface
between data terminal equipment and data
communications equipment for serial
binary data interchange. This is usually for
communications over a short distance (50
feet or less) and to a single device.
EIA/TIA-485 (Formerly RS-485) –
An Electronic Industries Association
(EIA)/Telecommunication Industry
Association (TIA) standard for electrical
characteristics of generators and receivers
for use in balanced digital multi-point
systems. This is usually used to
communicate with multiple devices over a
common cable or where distances over 50
feet are required.
Software
Information of data or program stored in
an easily changeable format. (RAM,
Floppy Disk, Hard Disk)
Space
Represents the transmission of a data bit
logic 0 (see logic level). Usually this is the
most positive voltage value in serial
communications.
Start Bit
A binary bit or logic level that represents
when the serial data information is about
to start (at the beginning of a character or
byte). This voltage level is positive.
Stop Bit
A binary bit or logic level that represents
when the serial data information is
complete (at the end of a character or
byte). This voltage level is negative.
Synchronous
When data is transmitted on a data line
and a clock signal is used on another line
to determine when to check the data line
for a logic level. This clock is said to
“synchronize” the data.
TCP/IP
Transmission Control Protocol/Internet
Protocol is a software protocol used to
send and receive data between different
computer systems. Standard protocol used
on the Internet.