This how-to is intended for Robotiq 2-Finger (85 or 140) version 2.x or 3.x, 3-Finger of any version and 2-Finger 200 of version 1.XThe basics :All Robotiq Grippers are communicating via Modbus RTU and are slave units. You can read it's status, or write commands. Sometimes, this signal is converted to an industrial fieldbus, but the registers and the control logic of the Gripper will stay the same.All our devices will use 16 bytes of 8 bits registers. Register numeration starts at zero (and not at 1).You can find each of the Gripper registers by consulting it's manual section 4 (control), see the 2-Finger registers or the 3-Finger registers.The details :See the blog post by @SebastienBelanger to give you an in-depth understanding of how our Grippers communicate and behave (with example).Note : you also have Modbus RTU and Modbus TCP examples inside each of the Gripper instruction manual section 4.Note 2 : you don't have to control the Gripper with it's registers when using Universal Robots, we've got a nice driver package for you that gives you only high level functions. See my post on UR Gripper control.