Williamsav Fm T55c Fm Plus Assistive Listening System Installation Guide

WILLIAMSAV FM T55C FM Plus Assistive Listening System

TELNET COMMAND GUIDE

(WF T5C, FM T55C)

The WaveCAST C (WF T5C) and FM+ C (FM T55C) can both be controlled remotely using Telnet commands.

Using Telnet

Telnet Server

• The FM_T55C Telnet server provides a single client connection on Port 23 to a Network Virtual Terminal (NVT), as implemented through the Telnet Protocol defined in RFC854.
• The NVT sends and receives 8-bit characters with the most significant bit set to 0; the remaining codes are reserved for the Telnet command set.
• End-of-line <EOL> is transmitted and expected to be received as the character sequence CR (0x0D) followed by LF (0x0A).
• To conserve network bandwidth, the FM_T55C Telnet server does not echo received characters. Command replies typically use a single TCP/IP packet.
• The server will automatically disconnect the client after 10 minutes of no port activity.

Telnet Clients
Although designed primarily as a machine-to-machine interface, the Telnet CLI may be accessed through one of several available Telnet terminal application programs. PuTTY is recommended as it can be easily configured for proper use. The Telnet terminal program provided by Microsoft Windows 10 is not recommended due to complications with configuration.

To configure PuTTY, create a session as follows:

• Set Host Name (or IP address) to match the IP address of the device.
• Set Port to ‘23’.
• Terminal Category:
  • Local Echo: Auto or Force on
  • Local Line Editing: Force on
• Connection Category:
  • Optionally set a keep-alive time.
    This prevents automatic disconnect when there is no port activity for more than 10 minutes.
  • Disable Nagle’s algorithm.
  • ◊ Set Internet protocol version to IPv4.
• Connection/Telnet options:
  • Handling OLD_ENVIRON ambiguity: BSD
  • Telnet negotiation mode: Active
  • Return key sends Telnet New Line instead of ^M.

Telnet CLI Login

Once a client has established a connection with the Telnet Server, an identifying message is sent to the client along with a request for a username and password. By default, these are set to “admin”, but may be changed once successfully logged in. Default credentials are restored when the unit is reset back to factory defaults.
The user is not given access to the Telnet Command Line Interface (CLI) until valid credentials have been received, insuring that no command is stored or executed otherwise.
The default username is admin. The default password is admin. Default credentials are restored when the unit is reset back to factory defaults.If the login information is incorrect, the message ERR:INVALID_ LOGIN is returned. After 3 unsuccessful attempts, the Telnet server disconnects the client.
A successful login is indicated by the return of a normal command prompt.

Command Format

All commands use the form <command category> <subcommand> [<parameter 1> …<parameter n>]. These items must be separated by ASCII space characters (0x20).

Command Parameters

Parameters may use one of 4 forms:

• Signed, 32-bit integers, entered as a string of characters representing decimal (base 10) values or 2’s complement hexadecimal values when prefixed by ‘0x’. These must be within a command’s valid range to be accepted.
• Literal character strings that serve to select between options. These must match as specified to be accepted.
• Free-form character strings. These may contain spaces by surrounding them in double quotes, e.g., ”A name with spaces“.
• IPv4 Addresses comprised of 4 unsigned integer octet values separated (without spaces) by periods, e.g. ‘192.168.1.2’ . IP Addresses must comply with this form to be accepted.

Command Execution

Together, <command category> and <subcommand> define a “command”. Execution of a command occurs upon reception of <EOL>.
For commands that can modify settings, including valid parameter(s) will change that setting. Omitting parameter(s) will return the current setting without modification. Example: server txmode fm<EOL> will change the mode to “fm”, whereas server txmode<EOL> simply returns the current audio transmitter mode.
Most read-only commands do not include parameters. Those that include parameters allow the user to specify an option for the returned value. Example: chan vu<EOL> returns the current VU value in a (default) front panel level format, whereas chan vu db<EOL> returns the current VU value in decibels.

Command Response

A command prompt, in the form of a chevron, e.g. ‘>’ is sent to the client as soon as the CLI is ready to process a new command. The client should typically wait to receive this character before sending a new command.
The response to a command is as follows:

• If a command’s format, syntax, or parameter range, etc. is incorrect, a corresponding error string is returned, terminated by an <EOL>.
• For valid commands that read a setting, the requested setting is returned, terminated by an <EOL>.
• For valid commands that change a setting, there is no reply. A new command prompt indicates acceptance.

It’s technically possible for the client to send multiple commands in succession without waiting for each response, but each command must be terminated by an <EOL> to be recognized as an individual command. Warning: This should only be considered for small groups of commands. With this kind of use, as the CLI input buffer is 256 NVT characters in size, it is possible to overrun the CLI input buffer. See Error Response “ERR:LINE_BUF_OVERFLOW”.

Error Responses

Syntax Notation

• Chevrons, i.e. “< >” surrounding an item denote it as a parameter. If the parameter is surrounded by brackets, i.e. “[ ]”, the parameter is optional.
• A vertical bar “|” between items signifies multiple parameter options.
• A parameter option shown surrounded by single quotes denotes it as a literal character sequence. The parameter must match to be accepted.
• A parameter that accepts a range of values is indicated by two values separated by an ellipsis, e.g. “2…25”.

Commands

VU Level Table

The VU level correspond to specific decibel ranges, and may cause issues when set too low or too high. Use the table below to pick an appropriate range for your venue’s audio.

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