LabWindows/CVI

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TCP Support Library Error Codes

TCP Support Library Error Codes

The TCP Support Library functions return negative values when they detect errors. TCP uses a common set of error codes and provides end-to-end error detection and correction and reliable data delivery. Specifically, TCP notifies the sender of packet delivery, guarantees that packets are delivered in the same order in which they were sent, retransmits lost packets, and ensures that data packets are not duplicated. TCP uses a checksum on both the headers and data of each segment to help detect network corruption. The following table lists the error codeserror codes, defined constants, and error messages associated with functions in the the LabWindows/CVI TCP Support Library.

Use the GetTCPErrorString function to convert the error code, returned in the status parameter of TCP Support Library functions, into meaningful error messages.

Note Note  Because errors can occur in the underlying Winsock or other operating system components, call GetTCPSystemErrorString to obtain a system message that describes the error. The system messages can be more descriptive than the TCP Support Library error codes. To obtain the correct system error message, you must call GetTCPSystemErrorString immediately after calling the TCP Support Library function that failed.

Error codes are defined in the cvi\include\tcpsupp.h file.

Value Code Error Message
0 -kTCP_NoError No Error
-1 -kTCP_UnableToRegisterService Unable to register service
-2 -kTCP_UnableToEstablishConnection Unable to establish connection
-3 -kTCP_ExistingServer Existing server
-4 -kTCP_FailedToConnect Failed to connect
-5 -kTCP_ServerNotRegistered Server not registered
-6 -kTCP_TooManyConnections Too many connections
-7 -kTCP_ReadFailed Read failed
-8 -kTCP_WriteFailed Write failed
-9 -kTCP_InvalidParameter Invalid parameter
-10 -kTCP_OutOfMemory Insufficient memory
-11 -kTCP_TimeOutErr Timeout error
-12 -kTCP_NoConnectionEstablished No connection established
-13 -kTCP_GeneralIOErr General I/O error
-14 -kTCP_ConnectionClosed Connection closed
-15 -kTCP_UnableToLoadWinsockDLL Unable to load Winsock DLL
-16 -kTCP_IncorrectWinsockDLLVersion Incorrect Winsock DLL version
-17 -kTCP_NetworkSubsystemNotReady Network subsystem not ready
-18 -kTCP_ConnectionsStillOpen Connections still open
-19 -kTCP_DisconnectPending Disconnection pending
-20 -kTCP_InfoNotAvailable Information not available
-21 -kTCP_HostAddressNotFound Host address was not found

Remarks

You can have a maximum of 255 concurrent conversations and 1,024 connections. If you exceed this limit, LabWindows/CVI returns -kTCP_TooManyConnections. You might not be able to open the maximum number of connections allowed by LabWindows/CVI because of limitations imposed by the operating system.

For functions that read or write data (ClientTCPRead, ClientTCPWrite, ServerTCPRead, ServerTCPWrite), the return value indicates the number of bytes transferred if the function was successful.

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