Lantronix Device Server MSS 485 User manual

MSS485 Installation Guide
For the Lantronix MSS485 Micro Serial Server

i
Contents
1 Introduction
1.1 RS-485 Networking Overview.................................1-2
1.1.1 RS-485 Protocols....................................1-2
1.1.2 Two-wire Mode.....................................1-2
1.1.3 Four-wire Mode....................................1-3
1.2 Terms...........................................................................1-4
1.3 Protocols......................................................................1-5
1.4 Software ......................................................................1-6
1.5 Configuration.............................................................1-6
2 Installation
2.1 MSS485 Components.................................................2-1
2.2 Installation ..................................................................2-3
2.2.1 Power-up Diagnostics..........................2-6
2.3 Is It Working?.............................................................2-7

ii
3 Getting Started
3.1 IP Address Configuration.........................................3-2
3.1.1 Using a BOOTP or RARP Reply.........3-2
3.1.2 Using an ARP Entry and the Ping Command3-
2
3.1.3 Using the Serial Console......................3-3
3.2 Incoming Logins ........................................................3-4
3.2.1 Controlling Incoming Logins..............3-4
3.2.2 EZWebCon Login and Configuration3-4
3.2.3 Other Incoming TCP/IP Logins.........3-4
3.2.4 Incoming LAT Logins ..........................3-5
3.3 Serial Port Logins.......................................................3-5
3.4 Remote Console Logins ............................................3-5
3.5 Starting Outbound Connections..............................3-6
3.5.1 Telnet......................................................3-6
3.5.2 SPX..........................................................3-7
3.5.3 LAT .........................................................3-7
3.6 Logout..........................................................................3-7
4 Configuration
4.1 Command Set.............................................................4-1
4.2 System Passwords .....................................................4-1
4.2.1 Privileged Password.............................4-1
4.2.2 Login Password.....................................4-2
4.3 Protocol Configuration .............................................4-2
4.3.1 TCP/IP Parameters ..............................4-2
4.3.2 IPX/SPX Parameters ............................4-3
4.3.3 LAT Parameters ....................................4-4
4.4 Serial Port Configuration.........................................4-4

iii
5 Using the MSS
5.1 Host-Initiated Connections ......................................5-2
5.1.1 Socket Connections...............................5-2
5.1.2 LAT Connections..................................5-3
5.1.3 Host Applications.................................5-4
5.1.4 Code Examples......................................5-4
5.2 Interactive Connections ............................................5-5
5.2.1 Session Control......................................5-5
5.2.2 Outgoing Connections.........................5-7
5.2.3 Status Displays......................................5-9
5.3 Emulating a Direct Serial Connection.....................5-11
5.4 Multihost Mode..........................................................5-13
A Technical Support
B Troubleshooting
C Pinouts
D Specifications
Warranty Statement
Declaration of Conformity
Index

Introduction
1 - 1
1 - Introduction
The MSS485 is a multiprotocol serial server that provides Ethernet
connections for devices connected to an RS-485 network.
This manual explains how to install the MSS.
• The remainder of this chapter outlines MSS functionality.
• Chapter 2, Installation , explains how to install the MSS hardware
and boot the server.
• Chapter 3, Getting Started , details different ways to log into the MSS
and prepare the server for configuration.
• Chapter 4, Configuration , covers basic configuration.
• Chapter 5, Using the MSS , provides an overview of how to use the
MSS interactively and with host applications.
• Appendices provide information on Technical Support,
Troubleshooting, Pinouts, and Specifications.
• The hypertext version of this manual, located on CD-ROM,
includes more specific information about configuring and using the
MSS and reloading MSS software.
Be sure to read the section of the configuration chapter that applies to the
protocol you are using (TCP/IP, IPX/SPX, or LAT).
For more detailed information on the MSS, including a complete
command reference, see the
MSS Reference Manual located on the CD in
HTML, PDF, and PostScript formats.
To access the HTMLversion of the Reference Manual on the CD, use your
web browser’s Open or Open File command (usually in the File menu)
to open the file index.htm in the root directory of the CD. Then click on the
link to the MSS Reference Manual .
The PostScript and PDF versions of the MSS485 manuals are located in
the manuals directory of the CD. Use the Adobe Acrobat Reader (widely
available on the Internet at no charge) to read and print all or parts of the
manual from the file mssref.pdf .

RS-485 Networking Overview Introduction
1 - 2
1.1 RS-485 Networking Overview
The RS-485 standard allows a transmission line to be shared like a “party
line.” As many as 32 devices can share the multidrop network. Typically,
one device is the master and the other devices are slaves. There are a few
important things to note about RS-485 networking with the MSS.
• The MSS can be used in either two-wire or four-wire mode. Refer
to the following sections to determine which mode to use.
• The maximum RS-485 network cabling length (without repeaters)
is 4,000 feet. Lantronix recommends the use of shielded twisted-
pair cabling.
1.1.1 RS-485 Protocols
A large number and variety of protocols run over RS-485. However, the
MSS does not convert or interpret serial data. It only moves data between
serial and Ethernet. Any RS-485 protocol will have to be implemented by
host software.
1.1.2 Two-wire Mode
In two-wire mode, the MSS operates in half duplex: one pair of wires
shares transmit and receive signals, and an optional third wire can be
used for shield/ground. The main advantage of using two-wire mode is
reduced cabling costs.
Figure 1-1: Example Two-wire Mode Network
•
•
•
•
TXA
TXB
TX
RX
Shield
A
A
B
B
A
B
B
A
RX
TX
Shield
Shield
Shield •
•
•
A
B
A
B
TX
RX Sh
Sh •
•••
•
•
A
B
A
B
TX
RX Sh
Sh •
•••
•
•
A
B
A
B
TX
RX Sh
Sh •
•••
•
Shield
Slave Slave Slave
Slave
MSS
(Master)

Introduction RS-485NetworkingOverview
1 - 3
On a two-wire RS-485 network, the MSS must turn its transmitter on
when it is ready to send data and then off a certain period of time after
the data has been sent so that the line is available to receive again. At
most baud rate settings, the timing delay is typically one character length
with a maximum of 1.5 character lengths.
NOTE: For 600 baud and 4800 baud operation, the timing delay is
doubled.
1.1.3 Four-wire Mode
In four-wire mode, the MSS operates in full duplex: one pair of wires
functions as the transmit pair, another pair of wires functions as the
receive pair, and there is a shield/ground wire for each pair. In a four-
wire RS-485 network, one device, such as the MSS, acts as master while
the other devices are slaves.
Figure 1-2: Example Four-wire Mode Network
It is important to connect the transmitter of the master device to the wire
that is connected to the receive terminals on the slave devices, and
connect the receiver of the master device to the wire that is connected to
the transmit terminals on the slave devices. In essence, the master device
will be connected to the slave devices with a
swapped cable.
The MSS transmitter is always driving and the receiver is always enabled,
so the MSS is able to send and receive data simultaneously. The
advantages of four-wire mode are double the throughput of two-wire
mode and a guaranteed open path to each slave device’s receiver.
TX
RX
RX
TX
TXA
TXB
RXB
RXA
Shield
Shield
TXA
TXB
RXB
RXA
Shield
Shield
ShA
A
B
B
TX
RX Sh
•
•
•
•
•
•
ShA
A
B
B
TX
RX Sh
•
•
•
•
•
•
ShA
A
B
B
TX
RX Sh
•
•
•
•
•
•
MSS
Slave Slave Slave
Slave
(Master)

Terms Introduction
1 - 4
1.2 Terms
In this manual, the following terms are used to describe parts of a network.
Host A computer attached to the network. The term
host is generally used to denote interactive
computers, or computers that people can log into.
Node Any intelligent device directly connected to the
Ethernet network such as a host, a printer, or a
terminal server.All nodes have their own Ethernet
addresses. The MSS is a node. Devices connected
to the MSS are not nodes.
Master The device that controlls all other devices on an
RS-485 network. An RS-485 network typically has
one master device.
Slave Any device on the RS-485 network that is not the
master.An RS-485 network can have up to 31 slave
devices.
Session A logical connection to a service. A typical session
is a terminal connected to a host through the
server.
Local mode The MSS user interface. It is used to issue
configuration and session management
commands and to establish connections. When in
Local mode, users will see a Local> prompt.

Introduction Protocols
1 - 5
1.3 Protocols
A network protocol is a method of communicating over the Ethernet.
Each protocol specifies a certain arrangement of data in the Ethernet
packets, and provides different services for its users. The MSS supports
the following protocols:
• TCP/IP
Support includes Telnet, Rlogin, UDP, and DNS. The Telnet
terminal protocol, supported on most UNIX systems, is an easy-
to-use interface that creates terminal connections to any network
host supporting Telnet. Rlogin is a protocol that allows users to
initiate a TCP/IP login session. UDP (User Datagram Protocol) is
a connectionless protocol that results in smaller packet headers,
no session overhead, and the ability to send to multiple hosts.
The MSS also supports the use of Domain Name Servers (DNS),
allowing a network nameserver to translate text node names into
numeric IP addresses.
The MSS also implements basic Simple Network Management
Protocol (SNMP) functionality. SNMP commands enable users,
usually system administrators, to get information from and
control other nodes on a local area network (LAN), and respond
to queries from other network hosts. The MSS allows
configuration of one community name with read/write access.
• IPX/ SPX (NetWare)
The MSS provides IPX/SPX access to the serial device from
NetWare and any other IPX/SPX nodes. It allows users to
download system files from NetWare hosts and log into the MSS
via NetWare for remote configuration.
The MSS supports all four NetWare frame types: Ethernet v2,
Native mode, 802.2, and 802.2 SNAP.
• Local Area Transport (LAT)
LAT is a protocol developed by Digital Equipment Corporation
(DEC) for local network connections and is supported on most
DEC operating systems. The MSS provides logins to remote hosts
and host-initiated connections, as well as access to the MSS serial
port from LAT hosts.