How to call .dll document in RTW

   I am using the Real time workshop(RTW) to create .exe software.I have chose "rtwin.tlc" as my "System target file", "rtwintmf" as my "Template makefile", "make_rtw" as my "Make command".
   In my .mdl document,I have used a S-function block in which it used some Windows API function。When the "build" button was pressed 
down,there were some errors reported in the Matlab comment window as follows:
   Could Anybody tell me how to solve this problom?

-export:GetBoards  
 Creating library ..\RTW_send.lib and object ..\RTW_send.exp 
rtwsend.obj : error LNK2001: unresolved external symbol __imp__htons@4 
rtwsend.obj : error LNK2001: unresolved external symbol __imp__inet_addr@4 
rtwsend.obj : error LNK2001: unresolved external symbol __imp__WSACleanup@0 
rtwsend.obj : error LNK2001: unresolved external symbol __imp__WSAGetLastError@0 
rtwsend.obj : error LNK2001: unresolved external symbol __imp__socket@12 
rtwsend.obj : error LNK2001: unresolved external symbol __imp__WSAStartup@8 
rtwsend.obj : error LNK2001: unresolved external symbol __imp__Sleep@4 
rtwsend.obj : error LNK2001: unresolved external symbol __imp__sendto@24 
rtwsend.obj : error LNK2001: unresolved external symbol __imp__closesocket@4 
..\RTW_send.rwd : fatal error LNK1120: 9 unresolved externals 
NMAKE : fatal error U1077: 'link' : return code '0x460' 
Stop.

Answer 1

[Kaustubha Govind]

According to this page in the Real-Time Windows Target (RTWT) documentation, Win32 API calls are not allowed in custom drivers blocks written for RTWT.

Regardless, to fix the linker error, you may just need to add the paths to the corresponding libraries to the model's Custom Code pane in the Real-Time Windows (or Code Generation) tab of the Configuration Parameters window.