each character surrounded by one or more start and stop bits which designate
the beginning and ending points of the information (see synchronous
(p. 530) ).
Indicates the sending and receiving devices are not synchronized using a
clock signal.
Term. baud rate
The rate at which data are transmitted.
Term. big endian
"Big end first." Placing the most significant integer at the beginning of a
numeric word, reading left to right. The processor in the CR1000 is MSB, or
puts the most significant integer first. See the appendix Endianness
(p. 643).
Term. cr
Carriage return
Term. data bits
Number of bits used to describe the data, and fit between the start and stop
bits. Sensors typically use 7 or 8 data bits.
Term. duplex
A serial communication protocol. Serial communications can be simplex,
half-duplex, or full-duplex.
Reading list: simplex
(p. 528), duplex (p. 248), half-duplex (p. 517), and full-duplex
(p. 516).
Term. lf
Line feed. Often associated with carriage return (<cr>). <cr><lf>.
Term. little endian
"Little end first." Placing the most significant integer at the end of a numeric
word, reading left to right. The processor in the CR1000 is MSB, or puts the
most significant integer first. See the appendix Endianness
(p. 643).
Term. LSB
Least significant bit (the trailing bit). See the appendix Endianness
(p. 643).
Term. marks and spaces
RS-232 signal levels are inverted logic compared to TTL. The different levels
are called marks and spaces. When referenced to signal ground, the valid RS-
232 voltage level for a mark is –3 to –25, and for a space is +3 to +25 with –3
to + 3 defined as the transition range that contains no information. A mark is
a logic 1 and negative voltage. A space is a logic 0 and positive voltage.
248
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