EZT-570S User Communication Reference Manual
A.5
Terms and Definitions (cont’d)
Slave –
A device that only responds to commands. This device never starts communication on its
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.
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.
Transmit –
To send data from one device to another. The device that sends the data is the
transmitter.
Word –
Two bytes make a word. This contains 16 bits.
