Simple Serial Transport

Native ports class serial. Serial __init__ ( port=None, baudrate=9600, bytesize=EIGHTBITS, parity=PARITY_NONE, stopbits=STOPBITS_ONE, timeout=None, xonxoff=False, rtscts=False, write_timeout=None, dsrdtr=False, inter_byte_timeout=None ) Parameters: • port – Device name or None. • baudrate () – Baud rate such as 9600 or 115200 etc. • bytesize – Number of data bits. Possible values:,,, • parity – Enable parity checking. Possible values:,,, • stopbits – Number of stop bits. Possible values:,, • timeout () – Set a read timeout value.

• xonxoff () – Enable software flow control. • rtscts () – Enable hardware (RTS/CTS) flow control. • dsrdtr () – Enable hardware (DSR/DTR) flow control.

• write_timeout () – Set a write timeout value. • inter_byte_timeout () – Inter-character timeout, None to disable (default). Raises: • ValueError – Will be raised when parameter are out of range, e.g. Baud rate, data bits. • SerialException – In case the device can not be found or can not be configured. The port is immediately opened on object creation, when a port is given.

It is not opened when port is None and a successive call to is required. Port is a device name: depending on operating system. /dev/ttyUSB0 on GNU/Linux or COM3 on Windows. The parameter baudrate can be one of the standard values: 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800, 9600, 19200, 38400, 57600, 115200. These are well supported on all platforms. Addison-Wesley Biology Lab Manual. Standard values above 115200, such as: 230400, 460800, 500000, 576000, 921600, 1000000, 1152000, 1500000, 2000000, 2500000, 3000000, 3500000, 4000000 also work on many platforms and devices. Non-standard values are also supported on some platforms (GNU/Linux, MAC OSX >= Tiger, Windows).

Though, even on these platforms some serial ports may reject non-standard values. Possible values for the parameter timeout which controls the behavior of: • timeout = None: wait forever / until requested number of bytes are received • timeout = 0: non-blocking mode, return immediately in any case, returning zero or more, up to the requested number of bytes • timeout = x: set timeout to x seconds (float allowed) returns immediately when the requested number of bytes are available, otherwise wait until the timeout expires and return all bytes that were received until then. Is blocking by default, unless write_timeout is set.

For possible values refer to the list for timeout above. Note that enabling both flow control methods ( xonxoff and rtscts) together may not be supported. It is common to use one of the methods at once, not both.

Dsrdtr is not supported by all platforms (silently ignored). Setting it to None has the effect that its state follows rtscts. Also consider using the function instead of creating Serial instances directly. Changed in version 3.0: numbers as port argument are no longer supported open ( ) Open port. Close ( ) Close port immediately. __del__ ( ) Destructor, close port when serial port instance is freed. The following methods may raise when applied to a closed port.

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Read ( size=1 ) Parameters: size – Number of bytes to read. Returns: Bytes read from the port.

Return type: bytes Read size bytes from the serial port. If a timeout is set it may return less characters as requested. With no timeout it will block until the requested number of bytes is read. Changed in version 3.0: renamed from flushOutput() send_break ( duration=0.25 ) Parameters: duration () – Time to activate the BREAK condition.

Send break condition. Timed, returns to idle state after given duration.

Break_condition Getter: Get the current BREAK state Setter: Control the BREAK state Type: bool When set to True activate BREAK condition, else disable. Controls TXD. When active, no transmitting is possible. Rts Setter: Set the state of the RTS line Getter: Return the state of the RTS line Type: bool Set RTS line to specified logic level. It is possible to assign this value before opening the serial port, then the value is applied uppon.

Dtr Setter: Set the state of the DTR line Getter: Return the state of the DTR line Type: bool Set DTR line to specified logic level. It is possible to assign this value before opening the serial port, then the value is applied uppon. Read-only attributes: name Getter: Device name. New in version 2.5. Cts Getter: Get the state of the CTS line Type: bool Return the state of the CTS line. Dsr Getter: Get the state of the DSR line Type: bool Return the state of the DSR line.

Ri Getter: Get the state of the RI line Type: bool Return the state of the RI line. Cd Getter: Get the state of the CD line Type: bool Return the state of the CD line New values can be assigned to the following attributes (properties), the port will be reconfigured, even if it’s opened at that time: port Type: str Read or write port. When the port is already open, it will be closed and reopened with the new setting. Baudrate Getter: Get current baud rate Setter: Set new baud rate Type: int Read or write current baud rate setting.

Bytesize Getter: Get current byte size Setter: Set new byte size. Possible values:,,, Type: int Read or write current data byte size setting. Parity Getter: Get current parity setting Setter: Set new parity mode. Possible values:,,, Read or write current parity setting.

Stopbits Getter: Get current stop bit setting Setter: Set new stop bit setting. Possible values:,, Read or write current stop bit width setting. Timeout Getter: Get current read timeout setting Setter: Set read timeout Type: float (seconds) Read or write current read timeout setting. Write_timeout Getter: Get current write timeout setting Setter: Set write timeout Type: float (seconds) Read or write current write timeout setting. Changed in version 3.0: renamed from interCharTimeout xonxoff Getter: Get current software flow control setting Setter: Enable or disable software flow control Type: bool Read or write current software flow control rate setting. Rtscts Getter: Get current hardware flow control setting Setter: Enable or disable hardware flow control Type: bool Read or write current hardware flow control setting.

Dsrdtr Getter: Get current hardware flow control setting Setter: Enable or disable hardware flow control Type: bool Read or write current hardware flow control setting. Rs485_mode Getter: Get the current RS485 settings Setter: Disable ( None) or enable the RS485 settings Type: or None Platform: Posix (Linux, limited set of hardware) Platform: Windows (only RTS on TX possible) Attribute to configure RS485 support. When set to an instance of and supported by OS, RTS will be active when data is sent and inactive otherwise (for reception). The class provides additional settings supported on some platforms. New in version 3.0.

The following constants are also provided: BAUDRATES A list of valid baud rates. The list may be incomplete, such that higher and/or intermediate baud rates may also be supported by the device (Read Only). BYTESIZES A list of valid byte sizes for the device (Read Only). PARITIES A list of valid parities for the device (Read Only). STOPBITS A list of valid stop bit widths for the device (Read Only). The following methods are for compatibility with the library.

Readable ( ) Returns: True. New in version 2.5. The port settings can be read and written as dictionary. The following keys are supported: write_timeout, inter_byte_timeout, dsrdtr, baudrate, timeout, parity, bytesize, rtscts, stopbits, xonxoff get_settings ( ) Returns: a dictionary with current port settings.

Return type: dict Get a dictionary with port settings. This is useful to backup the current settings so that a later point in time they can be restored using. Note that control lines (RTS/DTR) are part of the settings. Warning Programs using the following methods and attributes are not portable to other platforms!

Nonblocking ( ) Platform: Posix Configure the device for nonblocking operation. This can be useful if the port is used with. Note that must also be set to 0 fileno ( ) Platform: Posix Returns: File descriptor. Return file descriptor number for the port that is opened by this object. It is useful when serial ports are used with. Set_input_flow_control ( enable ) Platform: Posix Parameters: enable () – Set flow control state. Gurley Level Serial Numbers.

Manually control flow - when software flow control is enabled. This will send XON (true) and XOFF (false) to the other device. New in version 3.0. __init__(rts_level_for_tx=True, rts_level_for_rx=False, loopback=False, delay_before_tx=None, delay_before_rx=None): Parameters: • rts_level_for_tx () – RTS level for transmission • rts_level_for_rx () – RTS level for reception • loopback () – When set to True transmitted data is also received. • delay_before_tx () – Delay after setting RTS but before transmission starts • delay_before_rx () – Delay after transmission ends and resetting RTS rts_level_for_tx RTS level for transmission. Rts_level_for_rx RTS level for reception.

Loopback When set to True transmitted data is also received. Delay_before_tx Delay after setting RTS but before transmission starts (seconds as float). Delay_before_rx Delay after transmission ends and resetting RTS (seconds as float). RS485 A subclass that replaces the method with one that toggles RTS according to the RS485 settings.

Warning This implementation is currently in an experimental state. Use at your own risk. Class rfc2217. Serial This implements a compatible client. Port names are in the form: rfc2217://:[?[&]] This class API is compatible to with a few exceptions: • write_timeout is not implemented • The current implementation starts a thread that keeps reading from the (internal) socket.

The thread is managed automatically by the port object on open()/ close(). However it may be a problem for user applications that like to use select instead of threads. Due to the nature of the network and protocol involved there are a few extra points to keep in mind: • All operations have an additional latency time.

• Setting control lines (RTS/CTS) needs more time. • Reading the status lines (DSR/DTR etc.) returns a cached value. When that cache is updated depends entirely on the server.

The server itself may implement a polling at a certain rate and quick changes may be invisible. • The network layer also has buffers. This means that flush(), reset_input_buffer() and reset_output_buffer() may work with additional delay. Likewise in_waiting returns the size of the data arrived at the objects internal buffer and excludes any bytes in the network buffers or any server side buffer. • Closing and immediately reopening the same port may fail due to time needed by the server to get ready again. Not implemented yet / Possible problems with the implementation: • flow control between client and server (objects internal buffer may eat all your memory when never read). • No authentication support (servers may not prompt for a password etc.) • No encryption.

Due to lack of authentication and encryption it is not suitable to use this client for connections across the internet and should only be used in controlled environments. New in version 2.5. Class rfc2217. PortManager This class provides helper functions for implementing compatible servers. Basically, it implements everything needed for the protocol. It just does not open sockets and read/write to serial ports (though it changes other port settings). The user of this class must take care of the data transmission itself.

The reason for that is, that this way, this class supports all programming models such as threads and select. Usage examples can be found in the examples where two TCP/IP - serial converters are shown, one using threads (the single port server) and an other using select (the multi port server). Note Each new client connection must create a new instance as this object (and the protocol) has internal state.

__init__ ( serial_port, connection, debug_output=False ) Parameters: • serial_port – a instance that is managed. • connection – an object implementing write(), used to write to the network. • debug_output – enables debug messages: a instance or None. Initializes the Manager and starts negotiating with client in Telnet and protocol. The negotiation starts immediately so that the class should be instantiated in the moment the client connects. The serial_port can be controlled by commands.

This object will modify the port settings (baud rate etc.) and control lines (RTS/DTR) send BREAK etc. When the corresponding commands are found by the method. The connection object must implement a write() function. This function must ensure that data is written at once (no user data mixed in, i.e.

It must be thread-safe). All data must be sent in its raw form ( must not be used) as it is used to send Telnet and control commands. For diagnostics of the connection or the implementation, debug_output can be set to an instance of a (e.g. The caller should configure the logger using setLevel for the desired detail level of the logs. Escape ( data ) Parameters: data – data to be sent over the network. Returns: data, escaped for Telnet/ A generator that escapes all data to be compatible with. Implementors of servers should use this function to process all data sent over the network.

The function returns a generator which can be used in for loops. It can be converted to bytes using. Filter ( data ) Parameters: data – data read from the network, including Telnet and controls. Returns: data, free from Telnet and controls.

A generator that filters and processes all data related to. Implementors of servers should use this function to process all data received from the network. The function returns a generator which can be used in for loops. It can be converted to bytes using. Check_modem_lines ( force_notification=False ) Parameters: force_notification – Set to false. Parameter is for internal use. This function needs to be called periodically (e.g.

Every second) when the server wants to send NOTIFY_MODEMSTATE messages. This is required to support the client for reading CTS/DSR/RI/CD status lines. The function reads the status line and issues the notifications automatically. Constants Parity serial.

PARITY_NONE serial. PARITY_EVEN serial. PARITY_ODD serial. PARITY_MARK serial. PARITY_SPACE Stop bits serial. STOPBITS_ONE serial.

STOPBITS_ONE_POINT_FIVE serial. STOPBITS_TWO Note that 1.5 stop bits are not supported on POSIX. It will fall back to 2 stop bits. Byte size serial. FIVEBITS serial. SIXBITS serial. SEVENBITS serial.

EIGHTBITS Others Default control characters (instances of bytes for Python 3.0+) for software flow control: serial. XOFF Module version: serial. VERSION A string indicating the pySerial version, such as 3.0. Changed in version 3.0: removed, use serial.tools.list_ports instead serial. Serial_for_url ( url, *args, **kwargs ) Parameters: • url – Device name, number or • do_not_open – When set to true, the serial port is not opened.

Returns: an instance of or a compatible object. Get a native or a implementation of the Serial class, depending on port/url. This factory function is useful when an application wants to support both, local ports and remote ports. There is also support for other types, see section.

The port is not opened when a keyword parameter called do_not_open is given and true, by default it is opened. Warning This implementation is currently in an experimental state. Use at your own risk. This module provides classes to simplify working with threads and protocols.

Class serial.threaded. Protocol Protocol as used by the.

This base class provides empty implementations of all methods. Connection_made ( transport ) Parameters: transport – instance used to write to serial port. Called when reader thread is started. Data_received ( data ) Parameters: data ( bytes) – received bytes Called with snippets received from the serial port. Connection_lost ( exc ) Parameters: exc – Exception if connection was terminated by error else None Called when the serial port is closed or the reader loop terminated otherwise. Class serial.threaded.

Packetizer ( Protocol ) Read binary packets from serial port. Packets are expected to be terminated with a TERMINATOR byte (null byte by default). The class also keeps track of the transport. TERMINATOR = b' 0' __init__ ( ) connection_made ( transport ) Stores transport. Connection_lost ( exc ) Forgets transport. Data_received ( data ) Parameters: data ( bytes) – partial received data Buffer received data and search for TERMINATOR, when found, call. Handle_packet ( packet ) Process packets - to be overridden by subclassing.

Class serial.threaded. LineReader ( Packetizer ) Read and write (Unicode) lines from/to serial port. The encoding is applied. TERMINATOR = b' r n' ENCODING = 'utf-8' UNICODE_HANDLING = 'replace' handle_packet ( packet ) handle_line ( line ).

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