Schneider Optics Web Embedded Server - Manual (Page 82)

Ethernet Developers Guide
72 840 USE 115 00 Version 1.0
B.10 Transmit State Machine
The transmit state machine establishes a connection, and periodically transmits a
request. The different states for the transmit state machine are as follows.
z IDLE. In the IDLE state, there is no connection.
z
RESOLVING_NAME. In the RESOLVING_NAME state, CSample_View is
waiting for the window socket DLL to convert a node’s name into an IP
address.
z CONNECTING. In the CONNECTING state, CSample_View is waiting for the
window socket DLL to generate the FD_CONNECT event. This event
indicates if the attempt to establish a connection succeeded or failed.
z CONNECTED. The CONNECTED state indicates that a connection has been
successfully established.
z
WAIT_TO_TX. In the WAIT_TO_TX state, CSample_View is waiting to
transmit the message. It transmits the message, when the time from the last
transmit exceeds the specified poll interval.
z BLOCKED. When CSample_View attempts to send a message, the window
socket DLL may not be able to transmit the complete message. This is a flow
control condition, and CSample_View enters the BLOCKED state. The
window socket DLL generates the FD_WRITE event when it can send more
data.
z TX_DONE. CSample_View enters the TX_DONE when it has completed
transmitting the request.
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 OnManagConnect 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, OnMangConnect changes the transmit state to
RESOLVING_NAME, and it invokes the window sockets DLL
WSAAsyncGetHostByName function to resolve the name. Window sockets DLL
will generate the user defined WM_TCPIP_NAME_RESOLVED message which
indicates if the name has been resolved. The OnTcpIpNameResolved member
function process the WM_TCPIP_NAME_RESOLVED message. If the name is not
resolved, OnTcpIpNameResolved changes the transmit state back to IDLE.