Planar Wallnet, Настройка и эксплуатация

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TCP Versus UDP
TCP Versus UDP
Because of the different nature of TCP
connections and UDP datagrams (packets), the
behavior of the WallNet is slightly different
depending on whether the application is using a
TCP connection or UDP to send the display
commands.
Note: In the string values shown below, the
sequence “\r\n” indicates a CR+LF pair.
TCP Notes
• Only one simultaneous TCP connection is
supported.
• If WallNet receives an empty line (no
command text, followed by a CR or LF), it
responds with “# Clarity ASCII protocol server
ready (TCP).\r\n”.
• If WallNet receives a single Ctrl-D character
(0x04) on a TCP connection, it sends “# Ctrl-D
closing connection.\r\n” and then closes its
end of the connection. Ctrl-D is a traditional
character used to signal that a client is
finished using a telnet connection.
• If the data received by WallNet on a TCP
connection contains any non-printable ASCII
characters (other than Ctrl-D and CR or LF).
WallNet responds “# ERR illegal character in
input [<i>] = 0x<XX>\r\n” where <i> is the
zero-based index into the string at which the
bad character appeared. The <XX> is the
hexadecimal value of the bad character. The
UDP server does not scan character by
character so it will not emit this message.
• An easy way to test a TCP connection to the
ASCII Command Service is to use any telnet
client program to connect to the WallNet at
its IP address and port 57. Telnet clients
default to port 23, but always have a way to
specify an alternate port. For example,
common command-line telnet clients take an
optional port argument after the IP address,