TCP/IP Socket PropertiesDownload PDFSelected SectionSelected Section and Subsection(s)Entire ManualUpdated2025-07-305 minute(s) readLabVIEWAPI ReferenceLabVIEW G General Settings:Maximum Queue LengthSpecifies the maximum number of events that can be queued at any time on the given session. This property is read/write until the first time you call VISA Enable Event on a session. Thereafter, it is read only. The default is 50.General Settings:Resource ClassReturns the resource class of the resource string used to open the given session. For example, if the resource string for a given session is COM1 or ASRL1::INSTR, this property returns INSTR, regardless of the class of the I/O control.General Settings:Resource Lock StateReturns the current locking state of the resource associated with the given session. The resource can be unlocked, locked with an exclusive lock, or locked with a shared lock. The default is Unlocked.General Settings:Resource NameReturns the unique identifier for a resource.General Settings:Timeout ValueSpecifies the minimum timeout value, in milliseconds, to use when accessing the device. Note that the actual timeout that VISA returns may be higher than the one requested. The default is 2000.General Settings:User DataSpecifies a data value for the private use of an application. The VISA implementation stores this value in a per-session location, so that user data on other sessions does not affect the user data on this session. VISA does not use this property for any purpose.Interface Information:Interface DescriptionSpecifies human-readable text that describes the given interface. Note: Use the value of this property for display purposes only and not for programmatic decisions. The value can change between VISA implementations and/or revisions.Interface Information:Interface NumberReturns the board number for the given interface.Interface Information:Interface TypeSpecifies the interface type of the given session.Version Information:Resource Manufacturer IdentificationReturns a value that corresponds to the VXI manufacturer ID of the manufacturer that created the VISA implementation.Version Information:Resource Manufacturer NameReturns the name of the manufacturer that created the implementation. This is not related to the device manufacturer attributes. Note: Use the value of this property for display purposes only and not for programmatic decisions. The value can change between VISA implementations and/or revisions.Version Information:Version of ImplementationReturns the version of a given implementation. This value is defined by the individual manufacturer and increments with each new revision. The format of the value has the upper 12 bits as the major number of the version, the next lower 12 bits as the minor number of the version, and the lowest 8 bits as the sub-minor number of the version.Version Information:Version of SpecificationReturns the value that uniquely identifies the version of the VISA specification to which the implementation complies. The format of the value has the upper 12 bits as the major number of the version, the next lower 12 bits as the minor number of the version, and the lowest 8 bits as the sub-minor number of the version.Message Based Settings:File Append EnableSpecifies whether VISA Read To File appends or overwrites (truncates) when opening a file. If this property is set to TRUE, VISA Read To File appends when opening a file. If this property is set to FALSE, VISA Read To File overwrites (truncates) when opening a file. The default is FALSE.Message Based Settings:IO ProtocolSpecifies which protocol to use. In VXI, you can choose normal word serial or fast data channel. In GPIB, you can choose normal or high-speed HS-488 transfers. In serial, TCP/IP, or USB, you can choose normal transfers or 488.2-defined strings. In USBTMC, you can choose normal or vendor-specific transfers. The default is Normal.Message Based Settings:Send End EnableSpecifies whether to send an END indicator on the last byte of each write operation. This property is relevant only in VISA Write and related operations. The default is TRUE. On Serial Instr sessions, if this property is set to FALSE, the write transmits the exact contents of the user buffer, without modifying it and without appending anything to the data. If this property is set to TRUE, VISA performs the behavior described in the property End Mode for Writes (ASRL End Out). On GPIB, VXI, GPIB-VXI, TCP/IP Instr, and USB Instr sessions, if this property is set to TRUE, VISA includes the 488.2 defined end of message terminator.Message Based Settings:Suppress End EnableSpecifies whether to terminate a read operation due to an END condition. This property is relevant only in VISA Read and related operations. For all session types that support this property, if this property is set to TRUE, read does not terminate due to an END condition. However, a read may still terminate successfully if the Message Based Settings:Termination Character Enable (TermChar En) property is set to TRUE. Otherwise, read does not terminate until it receives all of the requested data (or an error occurs). The default is FALSE (except for TCP/IP Socket sessions). On Serial Instr sessions, if this property is set to FALSE, VISA performs the behavior described in the Serial Settings:End Mode for Reads (ASRL End In) property. On USB Raw sessions, if this property is set to FALSE, VISA performs the behavior described in the USB Settings:End Mode for Reads (USB End In) property. On TCP/IP Socket sessions, if this property is set to FALSE, if NI-VISA reads some data and then detects a pause in the arrival of data packets, it terminates the read operation. On TCP/IP Socket sessions, the default value for the property is TRUE in NI-VISA. On VXI Instr sessions, if this property is set to FALSE, the END bit terminates read operations.Message Based Settings:Termination CharacterSpecifies a character that, when read, causes a read operation to terminate. The termination character also must be enabled. This default is 0x0A (linefeed).Message Based Settings:Termination Character EnableSpecifies whether a read operation terminates when it receives the termination character. The default is FALSE.TCP/IP Settings:Computer HostnameReturns the host name of the device. If no host name is available, this property returns an empty string.TCP/IP Settings:Dot-Notation AddressReturns the TCPIP address of the device to which the session is connected. This string is formatted in dot notation.TCP/IP Settings:Keep-Alive PacketsSpecifies whether to use keep-alive packets on TCP connections. Setting this property to TRUE requests that a TCP/IP provider enable the use of keep-alive packets on TCP connections. After the system detects a dropped connection, VISA returns a lost connection error code on subsequent I/O calls on the session. The time required for the system to detect the dropped connection depends on the system and is not settable. The default is FALSE.TCP/IP Settings:No Packet DelaySpecifies whether the Nagle algorithm is enabled. The Nagle algorithm is disabled when this property is TRUE (and vice versa). The Nagle algorithm improves network performance by buffering written data until a full-size packet can be sent. This property is TRUE by default in VISA to verify that writes get flushed immediately.TCP/IP Settings:Port NumberReturns the port number for a given TCPIP address. For a TCPIP SOCKET resource, this is a required part of the address/resource string.TCP/IP Settings:Server Certificate Expiration DateReturns the expiration date of the server certificate. The form is ASN.1 UTCTime “YYMMDDhhmm[ss]Z.TCP/IP Settings:Server Certificate Is PerpetualIndicates the certificate does not expire.TCP/IP Settings:Server Certificate Issuer NameReturns the name of the CA that signed the certificate in RFC4514 format.TCP/IP Settings:Server Certificate Subject NameReturns the serial number and subject field from the certificate om RFC4514 format.TCP/IP Settings:TLS Cipher SuiteReturns a string that indicates the cipher suite used by TLS.
General Settings:Maximum Queue LengthSpecifies the maximum number of events that can be queued at any time on the given session. This property is read/write until the first time you call VISA Enable Event on a session. Thereafter, it is read only. The default is 50.General Settings:Resource ClassReturns the resource class of the resource string used to open the given session. For example, if the resource string for a given session is COM1 or ASRL1::INSTR, this property returns INSTR, regardless of the class of the I/O control.General Settings:Resource Lock StateReturns the current locking state of the resource associated with the given session. The resource can be unlocked, locked with an exclusive lock, or locked with a shared lock. The default is Unlocked.General Settings:Resource NameReturns the unique identifier for a resource.General Settings:Timeout ValueSpecifies the minimum timeout value, in milliseconds, to use when accessing the device. Note that the actual timeout that VISA returns may be higher than the one requested. The default is 2000.General Settings:User DataSpecifies a data value for the private use of an application. The VISA implementation stores this value in a per-session location, so that user data on other sessions does not affect the user data on this session. VISA does not use this property for any purpose.Interface Information:Interface DescriptionSpecifies human-readable text that describes the given interface. Note: Use the value of this property for display purposes only and not for programmatic decisions. The value can change between VISA implementations and/or revisions.Interface Information:Interface NumberReturns the board number for the given interface.Interface Information:Interface TypeSpecifies the interface type of the given session.Version Information:Resource Manufacturer IdentificationReturns a value that corresponds to the VXI manufacturer ID of the manufacturer that created the VISA implementation.Version Information:Resource Manufacturer NameReturns the name of the manufacturer that created the implementation. This is not related to the device manufacturer attributes. Note: Use the value of this property for display purposes only and not for programmatic decisions. The value can change between VISA implementations and/or revisions.Version Information:Version of ImplementationReturns the version of a given implementation. This value is defined by the individual manufacturer and increments with each new revision. The format of the value has the upper 12 bits as the major number of the version, the next lower 12 bits as the minor number of the version, and the lowest 8 bits as the sub-minor number of the version.Version Information:Version of SpecificationReturns the value that uniquely identifies the version of the VISA specification to which the implementation complies. The format of the value has the upper 12 bits as the major number of the version, the next lower 12 bits as the minor number of the version, and the lowest 8 bits as the sub-minor number of the version.Message Based Settings:File Append EnableSpecifies whether VISA Read To File appends or overwrites (truncates) when opening a file. If this property is set to TRUE, VISA Read To File appends when opening a file. If this property is set to FALSE, VISA Read To File overwrites (truncates) when opening a file. The default is FALSE.Message Based Settings:IO ProtocolSpecifies which protocol to use. In VXI, you can choose normal word serial or fast data channel. In GPIB, you can choose normal or high-speed HS-488 transfers. In serial, TCP/IP, or USB, you can choose normal transfers or 488.2-defined strings. In USBTMC, you can choose normal or vendor-specific transfers. The default is Normal.Message Based Settings:Send End EnableSpecifies whether to send an END indicator on the last byte of each write operation. This property is relevant only in VISA Write and related operations. The default is TRUE. On Serial Instr sessions, if this property is set to FALSE, the write transmits the exact contents of the user buffer, without modifying it and without appending anything to the data. If this property is set to TRUE, VISA performs the behavior described in the property End Mode for Writes (ASRL End Out). On GPIB, VXI, GPIB-VXI, TCP/IP Instr, and USB Instr sessions, if this property is set to TRUE, VISA includes the 488.2 defined end of message terminator.Message Based Settings:Suppress End EnableSpecifies whether to terminate a read operation due to an END condition. This property is relevant only in VISA Read and related operations. For all session types that support this property, if this property is set to TRUE, read does not terminate due to an END condition. However, a read may still terminate successfully if the Message Based Settings:Termination Character Enable (TermChar En) property is set to TRUE. Otherwise, read does not terminate until it receives all of the requested data (or an error occurs). The default is FALSE (except for TCP/IP Socket sessions). On Serial Instr sessions, if this property is set to FALSE, VISA performs the behavior described in the Serial Settings:End Mode for Reads (ASRL End In) property. On USB Raw sessions, if this property is set to FALSE, VISA performs the behavior described in the USB Settings:End Mode for Reads (USB End In) property. On TCP/IP Socket sessions, if this property is set to FALSE, if NI-VISA reads some data and then detects a pause in the arrival of data packets, it terminates the read operation. On TCP/IP Socket sessions, the default value for the property is TRUE in NI-VISA. On VXI Instr sessions, if this property is set to FALSE, the END bit terminates read operations.Message Based Settings:Termination CharacterSpecifies a character that, when read, causes a read operation to terminate. The termination character also must be enabled. This default is 0x0A (linefeed).Message Based Settings:Termination Character EnableSpecifies whether a read operation terminates when it receives the termination character. The default is FALSE.TCP/IP Settings:Computer HostnameReturns the host name of the device. If no host name is available, this property returns an empty string.TCP/IP Settings:Dot-Notation AddressReturns the TCPIP address of the device to which the session is connected. This string is formatted in dot notation.TCP/IP Settings:Keep-Alive PacketsSpecifies whether to use keep-alive packets on TCP connections. Setting this property to TRUE requests that a TCP/IP provider enable the use of keep-alive packets on TCP connections. After the system detects a dropped connection, VISA returns a lost connection error code on subsequent I/O calls on the session. The time required for the system to detect the dropped connection depends on the system and is not settable. The default is FALSE.TCP/IP Settings:No Packet DelaySpecifies whether the Nagle algorithm is enabled. The Nagle algorithm is disabled when this property is TRUE (and vice versa). The Nagle algorithm improves network performance by buffering written data until a full-size packet can be sent. This property is TRUE by default in VISA to verify that writes get flushed immediately.TCP/IP Settings:Port NumberReturns the port number for a given TCPIP address. For a TCPIP SOCKET resource, this is a required part of the address/resource string.TCP/IP Settings:Server Certificate Expiration DateReturns the expiration date of the server certificate. The form is ASN.1 UTCTime “YYMMDDhhmm[ss]Z.TCP/IP Settings:Server Certificate Is PerpetualIndicates the certificate does not expire.TCP/IP Settings:Server Certificate Issuer NameReturns the name of the CA that signed the certificate in RFC4514 format.TCP/IP Settings:Server Certificate Subject NameReturns the serial number and subject field from the certificate om RFC4514 format.TCP/IP Settings:TLS Cipher SuiteReturns a string that indicates the cipher suite used by TLS.
General Settings:Maximum Queue LengthSpecifies the maximum number of events that can be queued at any time on the given session. This property is read/write until the first time you call VISA Enable Event on a session. Thereafter, it is read only. The default is 50.General Settings:Resource ClassReturns the resource class of the resource string used to open the given session. For example, if the resource string for a given session is COM1 or ASRL1::INSTR, this property returns INSTR, regardless of the class of the I/O control.General Settings:Resource Lock StateReturns the current locking state of the resource associated with the given session. The resource can be unlocked, locked with an exclusive lock, or locked with a shared lock. The default is Unlocked.General Settings:Resource NameReturns the unique identifier for a resource.General Settings:Timeout ValueSpecifies the minimum timeout value, in milliseconds, to use when accessing the device. Note that the actual timeout that VISA returns may be higher than the one requested. The default is 2000.General Settings:User DataSpecifies a data value for the private use of an application. The VISA implementation stores this value in a per-session location, so that user data on other sessions does not affect the user data on this session. VISA does not use this property for any purpose.Interface Information:Interface DescriptionSpecifies human-readable text that describes the given interface. Note: Use the value of this property for display purposes only and not for programmatic decisions. The value can change between VISA implementations and/or revisions.Interface Information:Interface NumberReturns the board number for the given interface.Interface Information:Interface TypeSpecifies the interface type of the given session.Version Information:Resource Manufacturer IdentificationReturns a value that corresponds to the VXI manufacturer ID of the manufacturer that created the VISA implementation.Version Information:Resource Manufacturer NameReturns the name of the manufacturer that created the implementation. This is not related to the device manufacturer attributes. Note: Use the value of this property for display purposes only and not for programmatic decisions. The value can change between VISA implementations and/or revisions.Version Information:Version of ImplementationReturns the version of a given implementation. This value is defined by the individual manufacturer and increments with each new revision. The format of the value has the upper 12 bits as the major number of the version, the next lower 12 bits as the minor number of the version, and the lowest 8 bits as the sub-minor number of the version.Version Information:Version of SpecificationReturns the value that uniquely identifies the version of the VISA specification to which the implementation complies. The format of the value has the upper 12 bits as the major number of the version, the next lower 12 bits as the minor number of the version, and the lowest 8 bits as the sub-minor number of the version.Message Based Settings:File Append EnableSpecifies whether VISA Read To File appends or overwrites (truncates) when opening a file. If this property is set to TRUE, VISA Read To File appends when opening a file. If this property is set to FALSE, VISA Read To File overwrites (truncates) when opening a file. The default is FALSE.Message Based Settings:IO ProtocolSpecifies which protocol to use. In VXI, you can choose normal word serial or fast data channel. In GPIB, you can choose normal or high-speed HS-488 transfers. In serial, TCP/IP, or USB, you can choose normal transfers or 488.2-defined strings. In USBTMC, you can choose normal or vendor-specific transfers. The default is Normal.Message Based Settings:Send End EnableSpecifies whether to send an END indicator on the last byte of each write operation. This property is relevant only in VISA Write and related operations. The default is TRUE. On Serial Instr sessions, if this property is set to FALSE, the write transmits the exact contents of the user buffer, without modifying it and without appending anything to the data. If this property is set to TRUE, VISA performs the behavior described in the property End Mode for Writes (ASRL End Out). On GPIB, VXI, GPIB-VXI, TCP/IP Instr, and USB Instr sessions, if this property is set to TRUE, VISA includes the 488.2 defined end of message terminator.Message Based Settings:Suppress End EnableSpecifies whether to terminate a read operation due to an END condition. This property is relevant only in VISA Read and related operations. For all session types that support this property, if this property is set to TRUE, read does not terminate due to an END condition. However, a read may still terminate successfully if the Message Based Settings:Termination Character Enable (TermChar En) property is set to TRUE. Otherwise, read does not terminate until it receives all of the requested data (or an error occurs). The default is FALSE (except for TCP/IP Socket sessions). On Serial Instr sessions, if this property is set to FALSE, VISA performs the behavior described in the Serial Settings:End Mode for Reads (ASRL End In) property. On USB Raw sessions, if this property is set to FALSE, VISA performs the behavior described in the USB Settings:End Mode for Reads (USB End In) property. On TCP/IP Socket sessions, if this property is set to FALSE, if NI-VISA reads some data and then detects a pause in the arrival of data packets, it terminates the read operation. On TCP/IP Socket sessions, the default value for the property is TRUE in NI-VISA. On VXI Instr sessions, if this property is set to FALSE, the END bit terminates read operations.Message Based Settings:Termination CharacterSpecifies a character that, when read, causes a read operation to terminate. The termination character also must be enabled. This default is 0x0A (linefeed).Message Based Settings:Termination Character EnableSpecifies whether a read operation terminates when it receives the termination character. The default is FALSE.TCP/IP Settings:Computer HostnameReturns the host name of the device. If no host name is available, this property returns an empty string.TCP/IP Settings:Dot-Notation AddressReturns the TCPIP address of the device to which the session is connected. This string is formatted in dot notation.TCP/IP Settings:Keep-Alive PacketsSpecifies whether to use keep-alive packets on TCP connections. Setting this property to TRUE requests that a TCP/IP provider enable the use of keep-alive packets on TCP connections. After the system detects a dropped connection, VISA returns a lost connection error code on subsequent I/O calls on the session. The time required for the system to detect the dropped connection depends on the system and is not settable. The default is FALSE.TCP/IP Settings:No Packet DelaySpecifies whether the Nagle algorithm is enabled. The Nagle algorithm is disabled when this property is TRUE (and vice versa). The Nagle algorithm improves network performance by buffering written data until a full-size packet can be sent. This property is TRUE by default in VISA to verify that writes get flushed immediately.TCP/IP Settings:Port NumberReturns the port number for a given TCPIP address. For a TCPIP SOCKET resource, this is a required part of the address/resource string.TCP/IP Settings:Server Certificate Expiration DateReturns the expiration date of the server certificate. The form is ASN.1 UTCTime “YYMMDDhhmm[ss]Z.TCP/IP Settings:Server Certificate Is PerpetualIndicates the certificate does not expire.TCP/IP Settings:Server Certificate Issuer NameReturns the name of the CA that signed the certificate in RFC4514 format.TCP/IP Settings:Server Certificate Subject NameReturns the serial number and subject field from the certificate om RFC4514 format.TCP/IP Settings:TLS Cipher SuiteReturns a string that indicates the cipher suite used by TLS.