User guide

Ethernet Developers Guide
72
840 USE 115 00 Version 1.0
B.10 Transmit State Machine
The transmit state machine establishes a connection, and periodicall
y
transmits a
re
q
uest. The different states for the transmit state machine are as follows.
IDLE. In the IDLE state, there is no connection.
RESOLVING_NAME. In the RESOLVING_NAME state, CSample_View is
waitin
g
for the window socket DLL to convert a node’s name into an IP
address.
CONNECTING. In the CONNECTING state, CSample_View is waitin
g
for the
window socket DLL to
g
enerate the FD_CONNECT event. This event
indicates if the attempt to establish a connection succeeded or failed.
CONNECTED. The CONNECTED state indicates that a connection has been
successfull
y
established.
WAIT_TO_TX. In the WAIT_TO_TX state, CSample_View is waitin
g
to
transmit the messa
g
e. It transmits the messa
g
e, when the time from the last
transmit exceeds the specified poll interval.
BLOCKED. When CSample_View attempts to send a messa
g
e, the window
socket DLL ma
y
not be able to transmit the complete messa
g
e. This is a flow
control condition, and CSample_View enters the BLOCKED state. The
window socket DLL
g
enerates the FD_WRITE event when it can send more
data.
TX_DONE. CSample_View enters the TX_DONE when it has completed
transmittin
g
the re
q
uest.
If the CSample_View is in the IDLE state, and user selects either the connect menu
item, or the connect tool bar button, CSample_View OnMana
g
Connect function
attempts to establish connect with its tcpip_initate_connection function. This
function examines the remote destination and determines if it’s a name or an IP
address. If it’s a name, OnMan
g
Connect chan
g
es the transmit state to
RESOLVING_NAME, and it invokes the window sockets DLL
WSAAs
y
ncGetHostB
y
Name function to resolve the name. Window sockets DLL
will
g
enerate the user defined WM_TCPIP_NAME_RESOLVED messa
g
e which
indicates if the name has been resolved. The OnTcpIpNameResolved member
function process the WM_TCPIP_NAME_RESOLVED messa
g
e. If the name is not
resolved, OnTcpIpNameResolved chan
g
es the transmit state back to IDLE.