Specifications

Rockwell Automation Publication AG-SG001G-EN-P - April 2015 77
Glossary
The following terms and abbreviations are used throughout this manual.
For definitions of terms not listed here, refer to the Allen-Bradley Industrial
Automation Glossary, publication AG-7.1
.
ACK See Acknowledgment.
Acknowledgment An ASCII control character that indicates the transmission and acceptance of
data.
Asynchronous Transmission A method of serial transmission where characters may be transmitted at unequal
time intervals. Asynchronous transmission requires that each character contains
start/stop elements so the receiver can detect the start and end of each character.
BCC Block-Check Character. The 2's complement of the 8-bit sum (modulo-256
arithmetic sum) of all data bytes in a transmission block. It provides a means of
checking the accuracy of each message transmission.
Bridge An interface between links in a communication network that routes messages
from one link to another when a station on one link addresses a message to a
station on another link.
CRC Cyclic Redundancy Check. An error detection scheme in which all of the
characters in a message are treated as a string of bits representing a binary number.
This number is divided by a predetermined binary number (a polynomial) and
the remainder is appended to the message as a CRC character. A similar
operation occurs at the receiving end to prove transmission integrity.
CTS Clear-To-Send. A signal from the DCE that tells the transmitting device (DTE)
to start transmitting data.
ControlLogix I/O The integral I/O platform for the ControlLogix Series of programmable
automation controllers providing the system with the latest I/O technology
supporting customers control and information needs
ControlLogix System Applies the new producer/consumer networking model to the I/O architecture.
This means that the I/O modules produce information (both state and
diagnostic data) when needed, eliminating the need for processors to continually
poll I/O.
DCD Data Carrier Detect. A signal indicating that the carrier is being received from a
remote DCE.
DCE Data Communication Equipment 1) Equipment that provides the functions
required to establish, maintain, or terminate a connection.
2) The signal conversion and coding required for communication between data
terminal equipment and data circuits. Examples include modems, line drivers,
coaxial cable, and satellite links. DCE may or may not be an integral part of a
computer.
DF1 The Allen-Bradley asynchronous serial protocol.