Lantronix ETS Reference Manual - 2.2.3 Rs-422
Network Protocols
Concepts
2-2
2.2.3 RS-422
The ETS422PR supports RS-422 on all of its ports. RS-422 is different from RS-232 or RS-423 in that it is
a differential or balanced line interface standard. It is designed for longer cabling distances (approaching
4,000 feet) in noisier electrical environments, and it can be used in multi-drop networks with one driver and
up to ten receivers.
The maximum speed of the RS-422 ports on the ETS422PR is 230.4 kb/s, as with RS-423, but this rate can
be sustained over longer cable runs than possible on RS-232 or RS-423 connections.
RS-422 ports are interoperable with RS-423 ports, but not with RS-232. When connecting an RS-422 port
to an RS-423 port, you must be sure that your connector cable is properly configured. Please consult the
connector pinout drawings in Appendix C before making a connector cable.
2.3 Network Protocols
A network protocol describes the data contained in Ethernet packets. The network protocols provided by
the ETS are completely separate, other than the use of the Ethernet data layer. The following figure shows
the protocol stacks supported by the ETS.
Figure 2-1: Supported Network Protocols
There are three different Ethernet frame formats, one of which is subdivided:
◆
What is typically called Ethernet is technically referred to as Ethernet v2. This is the default frame
type for most TCP/IP, LAT, and MOP/NCP protocol stacks. It can also be used for NetWare.
◆
The IEEE 802.2 frame format comes with either a regular or a SNAP SAP (Service Access Point).
AppleTalk uses the SNAP format by default. Both types can be used by NetWare.
◆
NetWare 2.x and 3.x stations, by default, do not use any of these frame types. They use a native mode
format that is being phased out.
AppleTalk
LAN Manager
LAT
NetWare
TCP/IP
Printer
Access Pro-
tocol
SMB
LAT
NCP
Telnet/ Rlo-
gin/ RTEL/
lpd
ATP
NetBEUI
SPX
TCP
DDP
IPX
IP
Ethernet/IEEE 802.3 Data Layer