Gripper Connection and Disconnection

SUMMARY

Gripper Connection and Disconnection manages the gripper session lifecycle for reliable runtime communication.

This skill ensures robust setup and teardown of gripper communication channels before and after task execution.

UNITS

timeout_ms in milliseconds (Robotiq only, default 5000). Port numbers are unitless integers. simulation_prim_path is a USD path string.

The Skill

# Connect
gripper.connect(ip=gripper_ip, protocol="URCAP", timeout_ms=2000)

# Or connect to the matching articulation in a running Isaac Sim stage
gripper.connect(simulation_prim_path=prim_path)

# Disconnect
gripper.disconnect()

The Code

Safety first!

A real robot will faithfully do whatever you ask of it - so please take a moment to clear the workspace, keep an E-Stop within reach, and be ready to disconnect.

Operating real hardware is at your own risk.

Real

"""
Demonstrates connecting and disconnecting a parallel gripper.

Supports OnRobot and Robotiq grippers, and Isaac Sim.

Usage:
    python connection_and_disconnection.py --ip <GRIPPER_IP>
    python connection_and_disconnection.py --prim_path <PRIM_PATH>

Note:
    Experimental gripper support for Isaac Sim:  Robotiq 2F85 (USD-based simulation only); Schunk EGP and
    PZN+ are.
"""

import argparse
from loguru import logger

from telekinesis.synapse.tools.parallel_grippers import onrobot


def main(ip: str | None,
         protocol: str,
         prim_path: str | None) -> None:
    """Connects to an OnRobot gripper over real hardware or Isaac Sim, then disconnects."""

    #===================== Create Gripper ======================================
    gripper = onrobot.OnRobotRG6()

    try:
        #===================== Connect Gripper =================================
        if prim_path:
            gripper.connect(simulation_prim_path=prim_path)
        else:
            gripper.connect(ip=ip, protocol=protocol)
    except (ConnectionError, OSError) as e:
        logger.error(f"Error occurred: {e}")
    finally:
        gripper.disconnect()


if __name__ == "__main__":
    p = argparse.ArgumentParser(description="OnRobot gripper connect/disconnect")
    p.add_argument("--protocol",
                   choices=["MODBUS_TCP"],
                   default="MODBUS_TCP")
    p.add_argument("--ip", default=None, help="IP for OnRobot Gripper")
    p.add_argument("--prim_path", type=str, default=None,
                   help='Isaac Sim gripper prim path, e.g. "/World/onrobot_rg6"')
    args = p.parse_args()

    main(ip=args.ip,
         protocol=args.protocol,
         prim_path=args.prim_path)

Running the Example

Real

python connection_and_disconnection.py --ip 192.168.1.100

Isaac Sim

python connection_and_disconnection.py --prim_path /World/onrobot_rg6

For all options:

python connection_and_disconnection.py --help

Parameter Configuration

Connect

Robotiq 2F-85

Parameter	Type	Default	Description
ip	str	None	IP address of the gripper.
protocol	str	"URCAP"	"URCAP" (via a UR controller) or "MODBUS_RTU" (direct USB connection).
timeout_ms	int	5000	Connection timeout in milliseconds. Range: 1-120000.
verbose	bool	False	If True, enables verbose backend logging.
simulation_prim_path	str	None	USD path of the gripper in a running Isaac Sim stage, e.g. /World/robotiq_2f_85. Ignores every other argument when given.

OnRobot RG2 / RG6

Parameter	Type	Default	Description
ip	str	""	IP address of the gripper.
protocol	str	"MODBUS_TCP"	Only "MODBUS_TCP" is accepted.
simulation_prim_path	str	None	USD path of the gripper in a running Isaac Sim stage, e.g. /World/onrobot_rg6. Ignores every other argument when given.

Disconnect

This skill takes no input parameters.

Returns

Connect

This skill returns nothing (None).

Disconnect

This skill returns nothing (None).

Raises

Connect

Robotiq 2F-85

Exception	Condition
TypeError	An argument (ip, serial_port, protocol, timeout_ms) does not match its expected type
ValueError	protocol is not "URCAP" or "MODBUS_RTU", timeout_ms is outside [1, 120000], or the address required by the selected protocol (ip for URCAP, serial_port for MODBUS_RTU) is missing
RuntimeError	The backend connection fails

OnRobot RG2 / RG6

Exception	Condition
TypeError	An argument (ip, protocol, timeout_ms) does not match its expected type
ValueError	ip is empty, protocol is not "MODBUS_TCP", or timeout_ms is outside [1, 120000]
RuntimeError	The gripper model is not set (e.g. OnRobot instantiated directly instead of OnRobotRG2/OnRobotRG6), or the connection to the gripper fails

Disconnect

Exception	Condition
RuntimeError	The gripper is not connected

Where to Use the Skill

• Session setup - Call connect once at the start of every script before issuing any gripper commands
• Session teardown - Call disconnect at the end of every script to release the gripper session
• Error recovery - Re-connect after a communication fault to restore the control session

When Not to Use the Skill

Do not call connect or disconnect when:

• The gripper is already connected - connect on an active session overwrites the existing session; disconnect first if reconnecting intentionally
• Inside a tight control loop - establishing a session has latency; connect once at startup and reuse it throughout execution