Serial Instr PropertiesDownload PDFSelected SectionSelected Section and Subsection(s)Entire ManualUpdated2025-03-148 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.General Settings:Allow DMA TransfersSpecifies whether I/O accesses should attempt to use DMA (TRUE) or Programmed I/O (FALSE). In some implementations, this property may have global effects even though it is documented as a local property. This behavior affects performance and not functionality.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.Serial Settings:Allow TransmitSpecifies whether to allow transmission. If FALSE, the serial port suspends transmission as if an XOFF character has been received. If TRUE, it resumes transmission as if an XON character has been received. If XON/XOFF flow control (software handshaking) is not being used, FALSE is an invalid value. The default is TRUE.Serial Settings:Baud RateSpecifies the baud rate of the given communications port. The rate is represented as an unsigned 32-bit integer so that any baud rate can be used, but the communications port usually requires a commonly used rate such as 300, 1200, 2400, or 9600 baud.Serial Settings:Break LengthSpecifies the duration (in milliseconds) of the break signal asserted when End Mode for Writes (ASRL End Out) is set to Break (3). Valid values include 1-500. The default is 250. If you want to control the assertion state and length of a break signal manually, use the VISA Serial Break VI instead.Serial Settings:Data BitsSpecifies the number of data bits contained in each frame. Valid values include 5-8. The data bits for each frame are located in the low-order bits of every byte stored in memory.Serial Settings:Discard NUL CharactersSpecifies whether to discard each data byte whose value is 0. If this property is TRUE, read operations discard NUL characters. If this property is FALSE, read operations treat NUL characters as normal data characters. For binary transfers, set this property to FALSE. The default is FALSE.Serial Settings:End Mode for ReadsSpecifies the method used to terminate read operations. Valid values include: (0) None, (1) Last Bit, (2) TermChar. If the value is (2) TermChar, then the value of the property Termination Character Enable (TermChar En) is ignored. The default is (2) TermChar.Serial Settings:End Mode for WritesSpecifies the method used to terminate write operations. Valid values include: (0) None, (1) Last Bit, (2) TermChar, (3) Break. The default is (0) None.Serial Settings:Error Replacement CharacterSpecifies the character to use to replace incoming characters that arrive with errors (such as a parity error). The default is 0.Serial Settings:Flow ControlSpecifies the flow control method used for both transmitting and receiving data. Valid values include: (0) Flow None, (1) Flow XON/XOFF, (2) Flow RTS/CTS, (3) Flow XON/XOFF and RTS/CTS, (4) Flow DTR/DSR, (5) Flow XON/XOFF and DTR/DSR. Certain values or combinations of values may not be supported by all serial ports and/or operating systems.Serial Settings:Flow Control XOFF CharacterSpecifies the value of the XOFF character used for XON/XOFF flow control (both directions). If XON/XOFF flow control (software handshaking) is not being used, the value of this property is ignored. The default is 0x13 (Control-S).Serial Settings:Flow Control XON CharacterSpecifies the value of the XON character used for XON/XOFF flow control (both directions). If XON/XOFF flow control (software handshaking) is not being used, the value of this property is ignored. The default is 0x11 (Control-Q).Serial Settings:Is Port ConnectedReturns whether the port is properly connected to another port or device. This property is valid only with serial drivers developed by National Instruments and documented to support this feature with the corresponding National Instruments hardware.Serial Settings:Modem Line Settings:Break StateSets manual control of the serial port's break state. If asserted, this property suspends character transmission and places the transmission line in a break state until this property is unasserted. If you want VISA to send a break signal after each write operation automatically, use the Break Length (Break Len) and End Mode for Writes (ASRL End Out) properties instead. The default is Unasserted.Serial Settings:Modem Line Settings:Line CTS StateReturns the current state of the Clear To Send (CTS) input signal.Serial Settings:Modem Line Settings:Line DCD StateSpecifies the current state of the Data Carrier Detect (DCD) input signal. This is often used by modems to indicate the detection of a carrier (modem) on the phone line. This signal is also known as Receive Line Signal Detect (RLSD). This property is read only except when the Wire Mode property is set to RS232/DCE, or RS232/Auto with the hardware currently in the DCE state.Serial Settings:Modem Line Settings:Line DSR StateReturns the current state of the Data Set Ready (DSR) input signal.Serial Settings:Modem Line Settings:Line DTR StateAsserts or unasserts the Data Terminal Ready (DTR) output signal manually.Serial Settings:Modem Line Settings:Line RI StateSpecifies the current state of the Ring Indicator (RI) input signal. The RI signal is often used by modems to indicate that the telephone line is ringing. This property is read only except when the Wire Mode property is set to RS232/DCE or to RS232/Auto with the hardware currently in the DCE state.Serial Settings:Modem Line Settings:Line RTS StateAsserts or unasserts the Request To Send (RTS) output signal manually. When the flow control is set to hardware handshaking, it is invalid to change this property.Serial Settings:Number of Bytes at Serial PortReturns the number of bytes currently available at the serial port used by this session.Serial Settings:ParitySpecifies the parity used with every frame that is transmitted or received. Valid values include: (0) Parity None, (1) Parity Odd, (2) Parity Even, (3) Parity Mark, (4) Parity Space. Mark means that the parity bit exists and is always 1. Space means that the parity bit exists and is always 0.Serial Settings:Stop BitsSpecifies the number of stop bits used to indicate the end of a frame. Valid values include: (10) Stop One, (15) Stop One-and-a-Half, (20) Stop Two.Serial Settings:Wire ModeSpecifies the current wire/transceiver mode. For RS485 hardware, this property is valid only with the RS485 serial driver developed by National Instruments. For RS232 hardware, the values RS232/DCE and RS232/Auto are valid only with RS232 serial drivers developed by National Instruments and documented to support this feature with the corresponding National Instruments hardware. When this feature is not supported, RS232/DTE is the only valid value.
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.General Settings:Allow DMA TransfersSpecifies whether I/O accesses should attempt to use DMA (TRUE) or Programmed I/O (FALSE). In some implementations, this property may have global effects even though it is documented as a local property. This behavior affects performance and not functionality.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.Serial Settings:Allow TransmitSpecifies whether to allow transmission. If FALSE, the serial port suspends transmission as if an XOFF character has been received. If TRUE, it resumes transmission as if an XON character has been received. If XON/XOFF flow control (software handshaking) is not being used, FALSE is an invalid value. The default is TRUE.Serial Settings:Baud RateSpecifies the baud rate of the given communications port. The rate is represented as an unsigned 32-bit integer so that any baud rate can be used, but the communications port usually requires a commonly used rate such as 300, 1200, 2400, or 9600 baud.Serial Settings:Break LengthSpecifies the duration (in milliseconds) of the break signal asserted when End Mode for Writes (ASRL End Out) is set to Break (3). Valid values include 1-500. The default is 250. If you want to control the assertion state and length of a break signal manually, use the VISA Serial Break VI instead.Serial Settings:Data BitsSpecifies the number of data bits contained in each frame. Valid values include 5-8. The data bits for each frame are located in the low-order bits of every byte stored in memory.Serial Settings:Discard NUL CharactersSpecifies whether to discard each data byte whose value is 0. If this property is TRUE, read operations discard NUL characters. If this property is FALSE, read operations treat NUL characters as normal data characters. For binary transfers, set this property to FALSE. The default is FALSE.Serial Settings:End Mode for ReadsSpecifies the method used to terminate read operations. Valid values include: (0) None, (1) Last Bit, (2) TermChar. If the value is (2) TermChar, then the value of the property Termination Character Enable (TermChar En) is ignored. The default is (2) TermChar.Serial Settings:End Mode for WritesSpecifies the method used to terminate write operations. Valid values include: (0) None, (1) Last Bit, (2) TermChar, (3) Break. The default is (0) None.Serial Settings:Error Replacement CharacterSpecifies the character to use to replace incoming characters that arrive with errors (such as a parity error). The default is 0.Serial Settings:Flow ControlSpecifies the flow control method used for both transmitting and receiving data. Valid values include: (0) Flow None, (1) Flow XON/XOFF, (2) Flow RTS/CTS, (3) Flow XON/XOFF and RTS/CTS, (4) Flow DTR/DSR, (5) Flow XON/XOFF and DTR/DSR. Certain values or combinations of values may not be supported by all serial ports and/or operating systems.Serial Settings:Flow Control XOFF CharacterSpecifies the value of the XOFF character used for XON/XOFF flow control (both directions). If XON/XOFF flow control (software handshaking) is not being used, the value of this property is ignored. The default is 0x13 (Control-S).Serial Settings:Flow Control XON CharacterSpecifies the value of the XON character used for XON/XOFF flow control (both directions). If XON/XOFF flow control (software handshaking) is not being used, the value of this property is ignored. The default is 0x11 (Control-Q).Serial Settings:Is Port ConnectedReturns whether the port is properly connected to another port or device. This property is valid only with serial drivers developed by National Instruments and documented to support this feature with the corresponding National Instruments hardware.Serial Settings:Modem Line Settings:Break StateSets manual control of the serial port's break state. If asserted, this property suspends character transmission and places the transmission line in a break state until this property is unasserted. If you want VISA to send a break signal after each write operation automatically, use the Break Length (Break Len) and End Mode for Writes (ASRL End Out) properties instead. The default is Unasserted.Serial Settings:Modem Line Settings:Line CTS StateReturns the current state of the Clear To Send (CTS) input signal.Serial Settings:Modem Line Settings:Line DCD StateSpecifies the current state of the Data Carrier Detect (DCD) input signal. This is often used by modems to indicate the detection of a carrier (modem) on the phone line. This signal is also known as Receive Line Signal Detect (RLSD). This property is read only except when the Wire Mode property is set to RS232/DCE, or RS232/Auto with the hardware currently in the DCE state.Serial Settings:Modem Line Settings:Line DSR StateReturns the current state of the Data Set Ready (DSR) input signal.Serial Settings:Modem Line Settings:Line DTR StateAsserts or unasserts the Data Terminal Ready (DTR) output signal manually.Serial Settings:Modem Line Settings:Line RI StateSpecifies the current state of the Ring Indicator (RI) input signal. The RI signal is often used by modems to indicate that the telephone line is ringing. This property is read only except when the Wire Mode property is set to RS232/DCE or to RS232/Auto with the hardware currently in the DCE state.Serial Settings:Modem Line Settings:Line RTS StateAsserts or unasserts the Request To Send (RTS) output signal manually. When the flow control is set to hardware handshaking, it is invalid to change this property.Serial Settings:Number of Bytes at Serial PortReturns the number of bytes currently available at the serial port used by this session.Serial Settings:ParitySpecifies the parity used with every frame that is transmitted or received. Valid values include: (0) Parity None, (1) Parity Odd, (2) Parity Even, (3) Parity Mark, (4) Parity Space. Mark means that the parity bit exists and is always 1. Space means that the parity bit exists and is always 0.Serial Settings:Stop BitsSpecifies the number of stop bits used to indicate the end of a frame. Valid values include: (10) Stop One, (15) Stop One-and-a-Half, (20) Stop Two.Serial Settings:Wire ModeSpecifies the current wire/transceiver mode. For RS485 hardware, this property is valid only with the RS485 serial driver developed by National Instruments. For RS232 hardware, the values RS232/DCE and RS232/Auto are valid only with RS232 serial drivers developed by National Instruments and documented to support this feature with the corresponding National Instruments hardware. When this feature is not supported, RS232/DTE is the only valid value.
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.General Settings:Allow DMA TransfersSpecifies whether I/O accesses should attempt to use DMA (TRUE) or Programmed I/O (FALSE). In some implementations, this property may have global effects even though it is documented as a local property. This behavior affects performance and not functionality.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.Serial Settings:Allow TransmitSpecifies whether to allow transmission. If FALSE, the serial port suspends transmission as if an XOFF character has been received. If TRUE, it resumes transmission as if an XON character has been received. If XON/XOFF flow control (software handshaking) is not being used, FALSE is an invalid value. The default is TRUE.Serial Settings:Baud RateSpecifies the baud rate of the given communications port. The rate is represented as an unsigned 32-bit integer so that any baud rate can be used, but the communications port usually requires a commonly used rate such as 300, 1200, 2400, or 9600 baud.Serial Settings:Break LengthSpecifies the duration (in milliseconds) of the break signal asserted when End Mode for Writes (ASRL End Out) is set to Break (3). Valid values include 1-500. The default is 250. If you want to control the assertion state and length of a break signal manually, use the VISA Serial Break VI instead.Serial Settings:Data BitsSpecifies the number of data bits contained in each frame. Valid values include 5-8. The data bits for each frame are located in the low-order bits of every byte stored in memory.Serial Settings:Discard NUL CharactersSpecifies whether to discard each data byte whose value is 0. If this property is TRUE, read operations discard NUL characters. If this property is FALSE, read operations treat NUL characters as normal data characters. For binary transfers, set this property to FALSE. The default is FALSE.Serial Settings:End Mode for ReadsSpecifies the method used to terminate read operations. Valid values include: (0) None, (1) Last Bit, (2) TermChar. If the value is (2) TermChar, then the value of the property Termination Character Enable (TermChar En) is ignored. The default is (2) TermChar.Serial Settings:End Mode for WritesSpecifies the method used to terminate write operations. Valid values include: (0) None, (1) Last Bit, (2) TermChar, (3) Break. The default is (0) None.Serial Settings:Error Replacement CharacterSpecifies the character to use to replace incoming characters that arrive with errors (such as a parity error). The default is 0.Serial Settings:Flow ControlSpecifies the flow control method used for both transmitting and receiving data. Valid values include: (0) Flow None, (1) Flow XON/XOFF, (2) Flow RTS/CTS, (3) Flow XON/XOFF and RTS/CTS, (4) Flow DTR/DSR, (5) Flow XON/XOFF and DTR/DSR. Certain values or combinations of values may not be supported by all serial ports and/or operating systems.Serial Settings:Flow Control XOFF CharacterSpecifies the value of the XOFF character used for XON/XOFF flow control (both directions). If XON/XOFF flow control (software handshaking) is not being used, the value of this property is ignored. The default is 0x13 (Control-S).Serial Settings:Flow Control XON CharacterSpecifies the value of the XON character used for XON/XOFF flow control (both directions). If XON/XOFF flow control (software handshaking) is not being used, the value of this property is ignored. The default is 0x11 (Control-Q).Serial Settings:Is Port ConnectedReturns whether the port is properly connected to another port or device. This property is valid only with serial drivers developed by National Instruments and documented to support this feature with the corresponding National Instruments hardware.Serial Settings:Modem Line Settings:Break StateSets manual control of the serial port's break state. If asserted, this property suspends character transmission and places the transmission line in a break state until this property is unasserted. If you want VISA to send a break signal after each write operation automatically, use the Break Length (Break Len) and End Mode for Writes (ASRL End Out) properties instead. The default is Unasserted.Serial Settings:Modem Line Settings:Line CTS StateReturns the current state of the Clear To Send (CTS) input signal.Serial Settings:Modem Line Settings:Line DCD StateSpecifies the current state of the Data Carrier Detect (DCD) input signal. This is often used by modems to indicate the detection of a carrier (modem) on the phone line. This signal is also known as Receive Line Signal Detect (RLSD). This property is read only except when the Wire Mode property is set to RS232/DCE, or RS232/Auto with the hardware currently in the DCE state.Serial Settings:Modem Line Settings:Line DSR StateReturns the current state of the Data Set Ready (DSR) input signal.Serial Settings:Modem Line Settings:Line DTR StateAsserts or unasserts the Data Terminal Ready (DTR) output signal manually.Serial Settings:Modem Line Settings:Line RI StateSpecifies the current state of the Ring Indicator (RI) input signal. The RI signal is often used by modems to indicate that the telephone line is ringing. This property is read only except when the Wire Mode property is set to RS232/DCE or to RS232/Auto with the hardware currently in the DCE state.Serial Settings:Modem Line Settings:Line RTS StateAsserts or unasserts the Request To Send (RTS) output signal manually. When the flow control is set to hardware handshaking, it is invalid to change this property.Serial Settings:Number of Bytes at Serial PortReturns the number of bytes currently available at the serial port used by this session.Serial Settings:ParitySpecifies the parity used with every frame that is transmitted or received. Valid values include: (0) Parity None, (1) Parity Odd, (2) Parity Even, (3) Parity Mark, (4) Parity Space. Mark means that the parity bit exists and is always 1. Space means that the parity bit exists and is always 0.Serial Settings:Stop BitsSpecifies the number of stop bits used to indicate the end of a frame. Valid values include: (10) Stop One, (15) Stop One-and-a-Half, (20) Stop Two.Serial Settings:Wire ModeSpecifies the current wire/transceiver mode. For RS485 hardware, this property is valid only with the RS485 serial driver developed by National Instruments. For RS232 hardware, the values RS232/DCE and RS232/Auto are valid only with RS232 serial drivers developed by National Instruments and documented to support this feature with the corresponding National Instruments hardware. When this feature is not supported, RS232/DTE is the only valid value.