Specifications

Appendix C - Glossary of Terms RS-422 And RS-485 Applications Ebook
Page 123 of 137 Manual Documentation Number: <DocNumber>
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Serial Connector
The connector used for serial connections to/from a device is typically a
standard type of DB9 or DB25, but various connector types may be used, RJ-
11/RJ-12, 8-pin DIN, RJ-45 or DB37.
Common serial ports are RS-232, but RS-422 or RS-485 ports are available
using expansion cards or converters.
A USB port is serial, but is generally called a USB port, for Universal Serial Bus
since the port provides for external system expansion rather than internal
expansion using ISA or PCI bus. USB is a host/device bus, not a device/device
serial connection.
Serial Port
Usually a RS-232C serial port, but may be RS-422 or RS-485 connections. The
electrical connections to a computer or device.
In a serial port, a byte of data is transmitted or received one bit at a time.
Typical eight-bit data requires that 10 bits be transferred, one bit at a time. In
a eight-bit parallel port, data is transferred eight bits at once.
A USB port is a special type of host computer serial port. USB devices can
communicate with the host, but not with each other.
SG / Signal Ground
Signal Ground (SG) is the signal common for a serial or similar connector.
Single ended signals are referenced the common, and differential signal
receivers require the common reference to establish the common level
between transmitter and receiver. Signal Ground may be isolated from the
grounds on other devices or may be connected by some device or devices to
earth or AC mains ground. Signal Ground may be used as a reference to the (-
) minus side of a power supply.
Simplex Mode
Operating single direction or half duplex. A single fiber optic cable is a simplex
cable.