Communication protocols¶

BLISS implements the following communication protocols:

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 of standalone serial line communication

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

From YAML configuration file¶

YAML example

name: ser0
plugin: comm
serial:
  url: /dev/ttyS0
  eol: "\r\n"      # Note: use double quotes (and not single ones)

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

Tango Serial Line¶

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

- name: nvolpi5
  plugin: bliss
  class: Intraled
  serial:
    url: tango://id42/serial_133_232/08
    eol: "\r\n"       # Note: use double quotes (and not single ones)
    baudrate: 9600
    parity: "N"

Serial BLISS devices structure¶

Screenshot

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:
  - 160.103.14.92:5432
  - 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)

TCP proxy¶

tcp-proxy is a server allowing to share a socket connection between more than one Bliss controller. It runs in a processus distinc from bliss session.

It can be used to control a device that allows only one tcp connection.

This is typically the case of PI piezo or Keithley controllers.

Warning

This class does not perform serialization of the communication.

Note

tcp-proxy, not tcp_proxy ;-)

Configuration example for a Keithley:

- plugin: keithley
  keithleys:
    - name: k_pico1
      model: 6485
      tcp-proxy:
        external: False
        tcp:
            url: id14serial1.esrf.fr:9001
            timeout: 3
            eol: "\n"       # Note: use double quotes (and not single ones)
      sensors:
        - name: pico1
          address: 1
          nplc: 0.1
          auto_range: True
          zero_check: False
          zero_correct: False
          unit: pA

By default, at client initialization, Bliss will spawn a process tcp-proxy which will be shared by all bliss sessions using that tcp-proxy object.

Another alternative is to use external: True option and to start this process externally, via multivisor for example.

There are two option to externally start the tcp-proxy server:

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

Usage of external server allows:

to restart it without restarting the Bliss session
to put the server on another computer to use a private connection to the controller. (this can be usefull for delicate controllers like PI piezo controllers)
to debug communications with --debug or -d flag

Screenshot

Colors are available if rich python module is installed.

Example of standalone TCP communication

from bliss.comm.util import get_comm, TCP
conf = { "tcp": {"url": "192.168.0.1:3615"}, }
default_options = {"eol": b"\r"}
comm = get_comm(conf, ctype=TCP, **default_options)

Note

kill_proxy_server() function is provided in case of problem to force proxy to stop and restart.

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

Communication protocols¶

Helper function get_comm¶

From YAML configuration file¶

Within a controller¶

Serial line¶

YML configuration¶

Mandatory parameters¶

Optional parameters¶

Tango Serial Line¶

Serial BLISS devices structure¶

Ser2net¶

YML configuration¶

Mandatory parameters¶

Optional parameters¶

TCP socket¶

YML configuration¶

Mandatory parameters¶

Optional parameters¶

TCP proxy¶

UDP socket¶

GPIB¶

SCPI¶

Modbus¶

VXI11¶

Helper function `get_comm`¶