Chapter 5 URL Handlers

CHAPTER 5 URL Handlers 5.1 Overview The function serial_for_url() accepts the following types of URLs: Changed in version 3.0: Options are specified with ? and & instead of / Device names are also supported, e.g.: • /dev/ttyUSB0 (Linux) • COM3 (Windows) Future releases of pySerial might add more types. Since pySerial 2.6 it is also possible for the user to add protocol handlers using protocol_handler_packages. 5.2 rfc2217:// Used to connect to RFC 2217 compatible servers. All serial port functions are supported. Implemented by rfc2217. Serial. Supported options in the URL are: 37 pySerial Documentation, Release 3.4 • ign_set_control does not wait for acknowledges to SET_CONTROL. This option can be used for non compliant servers (i.e. when getting an remote rejected value for option 'control' error when connecting). • poll_modem: The client issues NOTIFY_MODEMSTATE requests when status lines are read (CTS/DTR/RI/CD). Without this option it relies on the server sending the notifications automatically (that’s what the RFC suggests and most servers do). Enable this option when cts does not work as expected, i.e. for servers that do not send notifications. • timeout=< value>: Change network timeout (default 3 seconds). This is useful when the server takes a little more time to send its answers. The timeout applies to the initial Telnet / RFC 2271 negotiation as well as changing port settings or control line change commands. • logging={debug|info|warning|error}: Prints diagnostic messages (not useful for end users). It uses the logging module and a logger called pySerial.rfc2217 so that the application can setup up logging handlers etc. It will call logging.basicConfig() which initializes for output on sys.stderr (if no logging was set up already). Warning: The connection is not encrypted and no authentication is supported! Only use it in trusted environments. 5.3 socket:// The purpose of this connection type is that applications using pySerial can connect to TCP/IP to serial port converters that do not support RFC 2217. Uses a TCP/IP socket. All serial port settings, control and status lines are ignored. Only data is transmitted and received. Supported options in the URL are: • logging={debug|info|warning|error}: Prints diagnostic messages (not useful for end users). It uses the logging module and a logger called pySerial.socket so that the application can setup up logging handlers etc. It will call logging.basicConfig() which initializes for output on sys.stderr (if no logging was set up already). Warning: The connection is not encrypted and no authentication is supported! Only use it in trusted environments. 5.4 loop:// The least useful type. It simulates a loop back connection to test applications or run the unit tests. Supported options in the URL are: • logging={debug|info|warning|error}: Prints diagnostic messages (not useful for end users). It uses the logging module and a logger called pySerial.loop so that the application can setup up logging handlers etc. It will call logging.basicConfig() which initializes for output on sys.stderr (if no logging was set up already). Chapter 5. URL Handlers pySerial Documentation, Release 3.4 5.5 hwgrep:// This type uses serial.tools.list_ports to obtain a list of ports and searches the list for matches by a regexp that follows the slashes (see Pythons re module for detailed syntax information). Note that options are separated using the character &, this also applies to the first, where URLs usually use ?. This exception is made as the question mark is used in regexp itself. Depending on the capabilities of the list_ports module on the system, it is possible to search for the description or hardware ID of a device, e.g. USB VID:PID or texts. Unfortunately, on some systems list_ports only lists a subset of the port names with no additional information. Currently, on Windows and Linux and OSX it should find additional information. Supported options in the URL are: • n=N: pick the N’th entry instead of the first • skip_busy: skip ports that can not be opened, e.g. because they are already in use. This may not work as expected on platforms where the file is not locked automatically (e.g. Posix). 5.6 spy:// Wrapping the native serial port, this protocol makes it possible to intercept the data received and transmitted as well as the access to the control lines, break and flush commands. It is mainly used to debug applications. Supported options in the URL are: • file=FILENAME output to given file or device instead of stderr • color enable ANSI escape sequences to colorize output • raw output the read and written data directly (default is to create a hex dump). In this mode, no control line and other commands are logged. • all also show in_waiting and empty read() calls (hidden by default because of high traffic). Example: import serial with serial.serial_for_url('spy:///dev/ttyUSB0?file=test.txt', timeout=1) as s: s.dtr = False s.write('hello world') s.read(20) s.dtr = True s.write(serial.to_bytes(range(256))) s.read(400) s.send_break() with open('test.txt') as f: print(f.read()) Outputs: 000000.002 000000.002 000000.002 000001.015 Q-RX DTR TX RX reset_input_buffer inactive 0000 68 65 6C 6C 6F 20 77 6F 0000 68 65 6C 6C 6F 20 77 6F 72 6C 64 72 6C 64 hello world hello world (continues on next page) 5.5. hwgrep:// pySerial Documentation, Release 3.4 (continued from previous page) 000001.015 DTR active 000001.015 TX 0000 00 ˓→.. 000001.015 TX 0010 10 ˓→.. 000001.015 TX 0020 20 ˓→./ 000001.015 TX 0030 30 000001.015 TX 0040 40 ˓→@ABCDEFGHIJKLMNO 000001.016 TX 0050 50 ˓→PQRSTUVWXYZ[\]^_ 000001.016 TX 0060 60 ˓→`abcdefghijklmno 000001.016 TX 0070 70 ˓→~. 000001.016 TX 0080 80 ˓→.. 000001.016 TX 0090 90 ˓→.. 000001.016 TX 00A0 A0 ˓→.. 000001.016 TX 00B0 B0 ˓→.. 000001.016 TX 00C0 C0 ˓→.. 000001.016 TX 00D0 D0 ˓→.. 000001.016 TX 00E0 E0 ˓→.. 000001.016 TX 00F0 F0 ˓→.. 000002.284 RX 0000 00 ˓→.. 000002.284 RX 0010 10 ˓→.. 000002.284 RX 0020 20 ˓→./ 000002.284 RX 0030 30 000002.284 RX 0040 40 ˓→@ABCDEFGHIJKLMNO 000002.284 RX 0050 50 ˓→PQRSTUVWXYZ[\]^_ 000002.284 RX 0060 60 ˓→`abcdefghijklmno 000002.284 RX 0070 70 ˓→~. 000002.284 RX 0080 80 ˓→.. 000002.284 RX 0090 90 ˓→.. 000002.284 RX 00A0 A0 ˓→.. 000002.284 RX 00B0 B0 ˓→.. 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F .............. 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F .............. 21 22 23 24 25 26 27 28 29 2A 2B 2C 2D 2E 2F !"#$%&'()*+,- 31 32 33 34 35 36 37 38 39 3A 3B 3C 3D 3E 3F 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F 51 52 53 54 55 56 57 58 59 5A 5B 5C 5D 5E 5F 61 62 63 64 65 66 67 68 69 6A 6B 6C 6D 6E 6F 71 72 73 74 75 76 77 78 79 7A 7B 7C 7D 7E 7F pqrstuvwxyz{|} 81 82 83 84 85 86 87 88 89 8A 8B 8C 8D 8E 8F .............. 91 92 93 94 95 96 97 98 99 9A 9B 9C 9D 9E 9F .............. A1 A2 A3 A4 A5 A6 A7 A8 A9 AA AB AC AD AE AF .............. B1 B2 B3 B4 B5 B6 B7 B8 B9 BA BB BC BD BE BF .............. C1 C2 C3 C4 C5 C6 C7 C8 C9 CA CB CC CD CE CF .............. D1 D2 D3 D4 D5 D6 D7 D8 D9 DA DB DC DD DE DF .............. E1 E2 E3 E4 E5 E6 E7 E8 E9 EA EB EC ED EE EF .............. F1 F2 F3 F4 F5 F6 F7 F8 F9 FA FB FC FD FE FF .............. 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F .............. 11 12 13 14 15 16 17 18 19 1A 1B 1C 1D 1E 1F .............. 21 22 23 24 25 26 27 28 29 2A 2B 2C 2D 2E 2F !"#$%&'()*+,- 31 32 33 34 35 36 37 38 39 3A 3B 3C 3D 3E 3F 41 42 43 44 45 46 47 48 49 4A 4B 4C 4D 4E 4F 51 52 53 54 55 56 57 58 59 5A 5B 5C 5D 5E 5F 61 62 63 64 65 66 67 68 69 6A 6B 6C 6D 6E 6F 71 72 73 74 75 76 77 78 79 7A 7B 7C 7D 7E 7F pqrstuvwxyz{|} 81 82 83 84 85 86 87 88 89 8A 8B 8C 8D 8E 8F .............. 91 92 93 94 95 96 97 98 99 9A 9B 9C 9D 9E 9F .............. A1 A2 A3 A4 A5 A6 A7 A8 A9 AA AB AC AD AE AF .............. B1 B2 B3 B4 B5 B6 B7 B8 B9 BA BB BC BD BE BF .............. 0123456789:; 0123456789:; (continues on next page) Chapter 5. URL Handlers pySerial Documentation, Release 3.4 (continued from previous page) 000002.284 ˓→.. 000002.284 ˓→.. 000002.284 ˓→.. 000002.284 ˓→.. 000002.284 RX 00C0 C0 C1 C2 C3 C4 C5 C6 C7 C8 C9 CA CB CC CD CE CF .............. RX 00D0 D0 D1 D2 D3 D4 D5 D6 D7 D8 D9 DA DB DC DD DE DF .............. RX 00E0 E0 E1 E2 E3 E4 E5 E6 E7 E8 E9 EA EB EC ED EE EF .............. RX 00F0 F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 FA FB FC FD FE FF .............. BRK send_break 0.25 Another example, on POSIX, open a second terminal window and find out it’s device (e.g. with the ps command in the TTY column), assumed to be /dev/pts/2 here, double quotes are used so that the ampersand in the URL is not interpreted by the shell: python -m serial.tools.miniterm "spy:///dev/ttyUSB0?file=/dev/pts/2&color" 115200 The spy output will be live in the second terminal window. New in version 3.0. 5.7 alt:// This handler allows to select alternate implementations of the native serial port. Currently only the POSIX platform provides alternative implementations. PosixPollSerial Poll based read implementation. Not all systems support poll properly. However this one has better handling of errors, such as a device disconnecting while it’s in use (e.g. USB-serial unplugged). VTIMESerial Implement timeout using VTIME/VMIN of TTY device instead of using select. This means that inter character timeout and overall timeout can not be used at the same time. Overall timeout is disabled when inter-character timeout is used. The error handling is degraded. Examples: alt:///dev/ttyUSB0?class=PosixPollSerial alt:///dev/ttyUSB0?class=VTIMESerial New in version 3.0. 5.8 Examples • rfc2217://localhost:7000 • rfc2217://localhost:7000?poll_modem • rfc2217://localhost:7000?ign_set_control&timeout=5.5 • socket://localhost:7777 • loop://?logging=debug • hwgrep://0451:f432 (USB VID:PID) • spy://COM54?file=log.txt • alt:///dev/ttyUSB0?class=PosixPollSerial 5.7. alt:// pySerial Documentation, Release 3.4 Chapter 5. URL Handlers