Appendix C: Glossary
Appendix C. Glossary
ADU—Application Data Unit.
ASCII—American Standard Code for Information Interchange.
Baud Rate—Number of bits per second.
CRC—Cyclical Redundancy Checking.
Data Bits—Number of bits per byte, normally 7 with Modbus ASCII, and 8 with Modbus RTU.
DHCP—Dynamic Host Configuration Protocol.
Flow Control—The process of managing the rate of data transmission between two nodes.
Function Code—A code field that tells the Modbus Hardened Serial Server what kind of action to perform. GUI—Graphical User Interface.
IP—Internet Protocol.
IPv4—Internet Protocol version 4.
LED—Light emitting diode. Used as a visual indicator.
LES431A—Modbus Hardened Serial Server, RS-232/RS-422/485 on serial port.
MBAP—MODBUS Application Protocol.
MEI—Multi Electrical Interface via RS-232/422/485.
Modbus—A request/reply protocol that offers services specified by function codes.
Modbus Gateway — A bridge to get from Modbus TCP to Modbus Serial.
Parity Bit—A binary digit that is added to ensure that the number of bits with value of one in a given set of bits is always even or odd. It may also be a Mark (1), or a Space (0).
PDU—Protocol Data Unit.
RS-232—Interface between data terminal equipment and data circuit-terminating equipment employing serial binary data interchange.
RS-422—Electrical characteristics of generators and receivers for use in balanced digital point-to-point systems. RS-485—Electrical characteristics of generators and receivers for use in balanced digital multipoint systems. RTU—Remote Terminal Unit.
Stop Bit—Number of bit times after a character is transmitted before the next character can start transmission. TCP—Transmission Control Protocol
Unit ID—Unit Identifier. This is the same as the slave’s address.
