Python GRPC client bindings

The poulpe_ethercat_controller crate provides a GRPC server and client interface that can be accessed by multiple clients at the same time, either in Rust or Python. The GRPC server is implemented in Rust and the client bindings are generated for both Rust and Python. The python bindings are implemented in poulpe_ethercat_py crate.

The simplest way of obtaining the python client is to pip install the code directly from the git the repository, using the tag corresponding to the version of the firmware that you are using. For example, if we use the 1.5.4 tag: (see the tags)

pip install git+https://github.com/pollen-robotics/poulpe_ethercat_controller.git@1.5.4#subdirectory=poulpe_ethercat_py --verbose

Note

This install procedure is available from the version 1.5.4 of the poulpe_ethercat_controller.

Installation from source

Provided that you already have the poulpe_ethercat_controller crate cloned and built, you can install the python client bindings from the source code. You can find more information on how to build the code in the installation and configuration section.

First place yourself in the poulpe_ethercat_py directory, and then you can build the python client bindings you can use the maturin tool.

maturin develop --release

Info

You will hav to use a virtual environment to install the client with the maturin command. So make sure to activate the virtual environment before running the command. We suggest using conda to create the virtual environment, but you can use venv or virtualenv as well.
conda create -n poulpe_ethercat python=3.10
conda activate poulpe_ethercat
pip install maturin

Once you have the virtual environment activated you can run the following command:

pip install maturin
maturin develop --release

This will install the python client in the current environment. And then you can open the notebooks in the notebooks folder and scripts in the scripts folder to see how to use the client. See the notebooks for more information.

The client is a wrapper around the GRPC client generated from the poulpe_ethercat_grpc/src/client.rs folder.

Simple example

Create a simple config file file_config.yaml with the following content:

ethercat:
  master_id: 0
  cycle_time_us: 1000 # us - cycle time of the ethercat 1/frequency
  command_drop_time_us: 5000 # us (5ms default) 
  watchdog_timeout_ms: 500 # ms (500ms default)
  mailbox_wait_time_ms: 10000 #ms  (1s default)

And then you can run the following python script:

from poulpe_ethercat_py import PyPoulpeRemoteClient, PyEthercatServer
import time

# launch the server first
server = PyEthercatServer()
server.launch_server("file_config.yaml")

# wait for the server to start
time.sleep(1.0)

# print all slaves in the network
devices = server.get_all_slaves_in_network()
print("Devices connected in the network: ")
for i,name in zip(devices[0],devices[1]):
    print("Slave {}: {}".format(i,name))


# connect to the server
slave_id = 0
no_axis = 3

print('Connecting on slave: {}'.format(slave_id))
# Create an instance of the client
client = PyPoulpeRemoteClient(server.addr, [slave_id], 0.001)

time.sleep(1.0)

devices = client.get_all_slaves_in_network()
print("Devices connected in the network: ")
for i,name in zip(devices[0],devices[1]):
    print("Slave {}: {}".format(i,name))

print("Slave {} compliancy is: {}".format(slave_id, client.get_torque_state(slave_id)))
print("Slave {} current position: {}".format(slave_id, client.get_position_actual_value(slave_id)))

which might output something like:

POULPE controller ready!
Devices connected in the network: 
Slave 1: RightWristOrbita3d
Slave 0: RightShoulderOrbita2d
Connecting on slave: 0
Slave 0 compliancy is: True
Slave 0 current position: [-0.0011222249595448375, 3.743586057680659e-05, 6.8065196501265746e-06]

Note

You can find the complete list of functions in the poulpe_ethercat_py crate in the poulpe_ethercat_py docs.
You can find mure examples of useing the python client in the poulpe_ethercat_py/notebooks directory. See the notebooks