EMAControl

EMAControl provides a user interface with which to control the robotic sample changer available at beameline P02.1.

Specifically it provides:

• A class which allows commands to be sent to the robot
• A set of functions which instruct the robot to perform samples changes

How do I use it?

After running setup.py, emaapi.py expects a configuration file which provides the hostname/IP address and the port to connect to the robot controller. By default this is located at ~/.robot.ini (see example_config.ini)

To work with the robot a user needs to include the following in their script:

from emaapi import robot_begin, robot_end, mount_sample, unmount_sample

robot_begin()
for sample_nr in range(1, 5): # Mounting samples 1-4
    mount_sample(sample_nr)
    # ... Do some science with the sample ...
    unmount_sample()
robot_end()

How does it work?

The functions are based on a set of calls developed by Mario Wendt and Michael Wharmby, which cover the needs of beamline users and staff to use the robot to mount a sample, measure a diffraction pattern (using other supporting libraries) and then transfer the sample back to the sample magazines. The functions work by sending string messages through a socket to the robot control server, where these messages are then interpretted and the appropriate VAL3 function called. The following is a list of the possible string commands which may be sent through the socket to the controller:

• setAxis - (?)
• next - move to next sample
• current - (?)
• gate - go to gate position (between magazines and diffractometer)
• home - go to home position (above the magazines)
• homing - (?)
• spinner - go to spinner position
• offside - go to offside position (at diffractometer, away from spinner)
• zero - go to zero position (?)
• pick - pick sample (?)
• release - open gripper (!)
• open - open gripper (!)
• close - close gripper
• powerOn - switch motor power on
• interrupt - interrupt a motion (? does this do anything?)
• restart - restart motion after interruption (? does this do anything?)
• powerOff - switch motor power off
• setSAM - (?)