Communication protocols

BLISS implements the following communication protocols:

• Serial line
• Ser2net
• TCP socket
• TCP proxy
• UDP socket
• GPIB
• Modbus
• VXI11
• SCPI

Helper function get_comm

To create the communication object, BLISS provides a unique helper function:

def get_comm(config, ctype=None, **opts)

This helper creates the communication object from the YAML configuration or a simple dictionary (config). If a communication option is not found in config, it will look in the default options dictionary opts. If the option cannot be found in either config or opts, the communication class will use its own default. The type of communication deduced from the configuration can by checked by providing the ctype argument.

Example with serial line

from bliss.comm.util import get_comm, SERIAL
config = { 'serial': {'url': '/dev/ttyS0'}, }
default_options = {'baudrate': 19200, 'eol': b'\r'}
comm = get_comm(config, ctype=SERIAL, **default_options)

From YAML configuration file

YAML example

name: ser0
plugin: comm
serial:
  url: /dev/ttyS0
  eol: "\\r\\n"

from bliss.config.static import get_config
ser0 = get_config().get('ser0')

Note

Notice that it requires the comm plugin.

Within a controller

YAML example

class: FooController
name: foo
serial:
  url: /dev/ttyS0

from bliss.comm.util import get_comm, SERIAL

class FooController:
    def __init__(self, config):
        self.config = config
        self._comm = None

    def _init_com(self):
        default_options = {'baudrate': 19200}
        self._comm = get_comm(self.config, ctype=SERIAL, **default_options)

Serial line

https://en.wikipedia.org/wiki/Serial_port

YML configuration

serial:
  url: /dev/ttyS0

Mandatory parameters

• url: serial device file name

Optional parameters

• baudrate:

  • Values: [1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200]
  • Default: 9600

• bytesize:

  • Values: [7 (true ASCII) , 8 (most cases)]
  • Default: 8

• dsrdtr: enable hardware flow control (DSR/DTR)

  • Values: [False, True]
  • Default: False

• eol: end-of-line string to READ data

  • Default: "\n"
  • Note: use double quotes (and not single ones)

• interCharTimeout: inter byte timeout setting

  • Default: None
  • NB: inter_byte_timeout in new PySerial version

• parity:

  • Values: ['N': none, 'O': odd, 'E': even, 'M': mark, 'S': space]
  • Default: 'N'

• port:

  • Default: same as url

• rtscts: enable hardware flow control (RTS/CTS)

  • Values: [False, True]
  • Default: False

• stopbits:

  • Default: 1

• timeout:

  • Default: 5.0

• writeTimeout:

  • Default: None

• xonxoff:

  • Values: [False, True]
  • Default: False

Example of standalone serial line communication

from bliss.comm.util import get_comm, SERIAL
config = { 'serial': {'url': '/dev/ttyS0'}, }
default_options = {'baudrate': 19200, 'eol': b'\r'}
comm = get_comm(config, ctype=SERIAL, **default_options)

Tango Serial Line

BLISS serial communication object can talk to a Tango Serial device server.

- name: nvolpi5
  plugin: bliss
  class: Intraled
  serial:
    url: tango://id13/serial_133_232/08
    eol: "\r\n"       # Note: use double quotes (and not single ones)
    baudrate: 9600
    parity: "N"

Serial BLISS devices structure

Ser2net

Ser2net (aka rfc2217) is a protocol to deport serial line over ethernet.

Such a remote serial line can be used in rfc2217 mode or ser2net mode.

ser2net mode allows to define the remote serial device to use in local config (considering a well configured ser2net server with control port)

rfc2217 mode uses the mapping “port <-> serial device” defined on the remote host in ser2net config file

YML configuration

serial:
  url: ser2net://lidXXX:29000/dev/ttyRP11

or:

serial:
  url: rfc2217://lidXXX:28001

Mandatory parameters

See serial line parameters

Optional parameters

See serial line parameters

TCP socket

YML configuration

tcp:
  url: 160.103.99.42
  eol: "\r\n"       # Note: use double quotes (and not single ones)

Mandatory parameters

• url: IP address or a fully qualified name
  • examples:
    • 160.103.14.92
    • zorglub.esrf.fr

Optional parameters

• port: target host’s port

  • example: 5025

• timeout:

  • Default: 5.0

• eol: end-of-line string to READ data

  • Default: "\n"
  • Note: use double quotes (and not single ones)

Example of standalone TCP socket

from bliss.comm.util import get_comm, TCP
conf = {"tcp": {"url": "trucmuch.esrf.fr"}}
opt = {"port":5025}
kom = get_comm(conf, ctype=TCP, **opt)
print(kom.write_readline(b"*IDN?\n"))

TCP proxy

tcp-proxy allows to share a socket connection between more than one Bliss controller.

Example for a Keithley:

- plugin: keithley
  keithleys:
    - name: k_pico1
      model: 6485
      tcp-proxy:
        tcp:
            url: id14serial1.esrf.fr:9001
            timeout: 3
            eol: "\n"
      sensors:
        - name: pico1
          address: 1
          nplc: 0.1
          auto_range: True
          zero_check: False
          zero_correct: False
          unit: pA

By default, bliss will spawn a process tcp-proxy which will be shared by all bliss sessions using that tcp-proxy. Another alternative is to start this process externally via multivisor for example. To start the tcp-proxy server, 2 options:

• by giving host / port : tcp-proxy --host id14serial1.esrf.fr --port 9001

• by giving beacon object name holding the tcp configuration : tcp-proxy --beacon-name k_pico1

In that case, the flag external : True has to be added in the config as in following example:

- plugin: keithley
  keithleys:
    - name: k_pico1
      model: 6485
      tcp-proxy:
        external: True    <-- external flag
        tcp:
            url: id14serial1.esrf.fr:9001
            timeout: 3
            eol: "\n"
      sensors:
        - name: pico1
          address: 1
          ...

UDP socket

TODO

GPIB

There are various ways to communicate with GPIB devices:

• GPIB PCI board
  • locally if BLISS runs on the same computer than the GPIB driver
  • remotely if BLISS runs on another computer
• GPIB ethernet device: Enet box

Example of GPIB communication with PCI GPIB board and tango device server:

gpib:
  url: tango_gpib_device_server://id42/gpib_lid421/0
  pad: 13
  timeout: 10.

Example of GPIB communication with Enet device:

gpib:
  url: enet://gpibid42a.esrf.fr
  pad: 15
  timeout: 3.

Example of standalone GPIB communication

from bliss.comm.util import get_comm, GPIB
conf = {"gpib": {"url": "enet://gpibid42a.esrf.fr"}}
opt = {"pad":12}
kom = get_comm(conf, ctype=GPIB, **opt)
print(kom.write_readline(b"*IDN?\n"))

SCPI

TODO

Modbus

TODO

VXI11

TODO