/tango-training

MaxIV Kits cafe: How to create a PyTango device server

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About this repository

This repository is an example of a tango device server.

This tango device server is suppose to control a virtual scope throught tcp/ip.

The project contains:

  • An utils folder with:
    • tcp server (utils/tcp_server.py) which serves a dummy scope.
    • A dummy plc tango device that pushes event.
  • A tests folder that contains a test protocol. It can be used to validate the required features.
  • A training python package which contains an empty tango device file and a basic example of a possible implementation (Please look at it only after the training session)

The TCP server:

Protocol

  • Request should end with b'\n'
  • Get scope state:
    • request: b'STATE\n'
    • reply: b'State:ON\n' or b'State:OFF\n'
  • Turn acquisition on:
    • request: b'ON\n'
    • reply: b'State:ON\n'
  • Turn acquisition off:
    • request: b'OFF\n'
    • reply: b'State:OFF\n'
  • Get Waveform:
    • request: b'DATA\n'
    • reply example: b'Data:2.938672855118084e-10, 1.9815536275824104e-10, ...., 3.88063288479267e-10\n''

Basic shell client

This protocol can be test from the linux shell with a basic tcp client:

$ nc host port
ON
State:ON

Basic python script

from telnetlib import Telnet

telnet = Telnet()
telnet.open(host, port)
telnet.write(b"ON\n")
print(telnet.read_until(b"\n"))
telnet.close()

GOALS:

PyTango documentation

1 - Run the tango device

Validation:

  • tests/test_device.py::test_server_running: PASSED

2 - Connection with tango properties

Requires:

  • tango property: host
  • tango property: port

Validation:

  • tests/test_device.py::test_server_running: PASSED

3 - Start/Stop acquisition

Requires:

  • Tango command "TurnOn" (start the acquisition)
  • Tango command "TurnOff" (stop the acquisition)
  • Tango State handling:
    • FAULT if the connection failed
    • ON if the scope is acquiring
    • OFF if the scope is not acquiring

Validation:

  • tests/test_device.py::test_on_state
  • tests/test_device.py::test_off_state

4 - Expose waveform as tango attribute

Requires:

  • A Tango spectrum float attribute named "waveform".
  • It should be not allowed to read this attribute if the scope is not acquiring.

Validation:

  • tests/test_device.py::test_wavefrom_attribute

5 - Expose the maximum value as tango attribute

Requires:

  • A Tango scalar float attribute named "maximum"

Validation:

  • tests/test_device.py::test_maximum_attribute

6 - Add an offset to the waveform

Requires:

  • Tango writable scalar float attribute named "offset"
  • Add the offset setpoint to the waveform tango attribute

Validation:

  • tests/test_device.py::test_offset_attribute

7 - Control the communication rate

Requires:

  • Tango expert polled command named "Update"
  • The Update command should manage the tcp request.

Subscribe to a PLC alarm tag:

Requires:

  • Add a alarm tag attribute: test/fakeplc/1/fb_r1_105s_dia_rto_ad__inalarm
  • Switch the tango State to Alarm if the tag is raised

Test

Run with setup.py:

$ python3 setup.py test

Test state:

  • xfail: The feature is not implemented.
  • ERROR: The test has failed.
  • PASSED: The test succeed.

Add extra test argument:

$ python3 setup.py --addopts "-k test_server_running"

(The previous command line runs only the test named test_server_running)

Build

Build rpm package from jenkins

Jenkins job

Build using setup.py

python setup build

Installation

Install from maxiv rpm repository

$ sudo yum makecache --enablerepo=maxiv-testing
$ sudo yum install tangods-training --enablerepo=maxiv-testing

Install from sources in the user space:

$ python setup.py install --user