Basic control in Python

The shortest program that drives the gripper: it connects through the CANvas adapter, clears the errors, calibrates, then closes and opens every three seconds and prints what the gripper answers. It is the example from the product repository's README, with a longer wait for the calibration: the README's 4 s is too short for the 150 and 200 mm rails, and a move command sent while the calibration still runs ends it. pip install Spectral-BLDC is the only requirement. Change COM20 to your adapter's port (/dev/ttyACM0 on Linux) and node_id to the gripper's CAN ID if you changed it from 0.

Danger

700 mA closes the jaws with real force, about 14 N with the 21.5 mm stepper and 25 N with the 60 mm. Keep fingers out of the jaws, and start with a lower current if the gripper is new to you.

import Spectral_BLDC as Spectral
import time

Communication1 = Spectral.CanCommunication(bustype='slcan', channel='COM20', bitrate=1000000)
Motor1 = Spectral.SpectralCAN(node_id=0, communication=Communication1)

Motor1.Send_Clear_Error()
Motor1.Send_gripper_calibrate()
time.sleep(10)                 # the calibration: up to about ten seconds; send nothing meanwhile

temp_var = 0
while True:
   if temp_var == 0:
      Motor1.Send_gripper_data_pack(50,100,700,1,1,0,0)
      temp_var = 1
   elif temp_var == 1:
      Motor1.Send_gripper_data_pack(240,100,700,1,1,0,0)
      temp_var = 0

   message, UnpackedMessageID = Communication1.receive_can_messages(timeout=0.2)

   if message is not None:
      print(f"Message is: {message}")
      print(f"Node ID is : {UnpackedMessageID.node_id}")
      print(f"Message ID is: {UnpackedMessageID.command_id}")
      print(f"Error bit is: {UnpackedMessageID.error_bit}")
      print(f"Timestamp is: {message.timestamp}")

   time.sleep(3)

Each answer printed is the one to the command just sent, so it still shows the state from before that move. The arguments of Send_gripper_data_pack, in order: the position (0 open, 255 closed), the speed (0 to 255), the current limit in mA (the force), then the activate bit, the action bit, the E-stop bit and the release direction. With Python explains the library's calls, How the gripper works the state the gripper answers with, and Force and speed what the current means in newtons.

Comments

---

Found a mistake on this page? Edit it on GitHub · Report it · Get help · This page as Markdown · llms.txt · The whole manual as PDF