MANUAL IM635
Remote Operation
Page 14
The TELNET server communicates using the standard port 23 typically used by the TELNET protocol. The
implementation is a reduced-functionality version and does not support the full protocol, but it should function
properly with many clients. The server only supports a single connection, does not require any login, and does
not support options negotiation except for the initial state of the echo setting. The server does support an
inactivity timeout, and allows the use of TELNET NOP commands sent by the client to keep a session open. By
default, the timeout is set for 300 seconds (5 minutes), after which the server will automatically close the session
if no activity has occurred. Many of these features are configurable by the user (see SET TELNET in the command
reference). The status of the server can be seen using the SHOW NET TELNET command. An active TELNET
connection may be closed from the telnet application on the client using the 'QUIT' command. The unit provides a
TCP server that can be used for control and status of the unit using the same text-based messages used by the
serial port. By default, the server is configured to support a single connection and listen on a single port (port
10001), however the number of allowable connections can be changed to support up to 4 simultaneous users.
Server settings, such as the number of connections, port number, keepalive timeout, inactivity close timer, and
character echoing are programmable by the user (see SET TCP in the command reference). The status of the
server(s) can be seen using the SHOW NET TCP command.
A UDP server is also provided that will accept command messages sent via UDP protocol using the same text-
based messaging. UDP is a connection-less based protocol that is simpler and has less overhead than TCP. By
default, the internal UDP server listens on port 20000, but this can be changed via the SET UDP SERVER
command. It is important to note that UDP messages are not buffered, so sufficient time must be allowed
between messages for the command to execute or a command/response scheme should be implemented to
synchronize the messages.
Various network events generate status messages shown on the serial Console port. These events include TCP
and TELNET server connect/disconnect messages and DHCP/AUTOIP address assignment changes. The status
messages may be disabled if desired (see SET NETSTAT), but are enabled by default.
For simple device discovery, the Microchip Announce protocol is used. The Microchip Announce protocol is a UDP
based scheme used to detect devices supporting the protocol. The protocol broadcasts UDP packets to port
30303 containing the message, "Discovery: Who is out there?", and supporting devices respond with a UDP
packet which provides the device IP and MAC address, as well as other info such as the firmware version. A copy
of the Ethernet Device Discoverer application for MS Windows-based systems is provided on the CD supplied with
unit, or can be downloaded from the Microchip website.
4.4.
USB
The USB port provides a USB Communications Device Class device (CDC) interface that allows programming via a
virtual COM port using the same text-based commands as the serial port. For interaction with a terminal
emulator, a console mode command-line interface (CLI) is provided for ease of use, and is user-configurable via
the USB CONSOLE command. Refer to paragraph 4-14 for information on installing the USB CDC driver file.
4.5.
GPIB
An optional GPIB interface is available on some units allowing for control via an IEEE-488 controller, and
implements the functionality of IEEE488.2 standard protocol. The GPIB bus address is user programmable via the
SET GPIB ADDR command or via the front-panel (if installed). The default address is set to 10.
