3.Control

3.1.Use xArm Studio to Control xArm Gripper

1. Set up xArm Gripper

• Control the xArm gripper in the live control

Control Method:

1. By dragging this progress bar, you can control the opening and closing stroke of the gripper.

• Control the xArm gripper through Blockly

Find the example file 1007_xArm_Gripper in the blockly module

The role of this program: execute this program to control the gripper to pick the target object at the specified position, and then place the target object at the target position.

Note:

1. When the gripper is installed on the robotic arm, the TCP Payload of the gripper should be set in the Blockly program. When the total weight of the gripper changes after the object is picked, a new TCP Payload needs to be set.

3.2.Use Python-SDK to Control xArm Gripper

For details on controlling Gripper with python-SDK, please refer to the link below:

https://github.com/xArm-Developer/xArm-Python-SDK/blob/master/example/wrapper/common/5004-set_gripper.py

3.3.Use ROS-SDK to Control xArm Gripper

Please refer to Section 5.7.7 in the ReadMe file attached to the ROS package to control the gripper. xArm ROS-SDK link :

https://github.com/xArm-Developer/xarm_ros

3.4.Use Private Protocol Communication Protocol to Control xArm Gripper

This section mainly explains how to control the xArm Gripper by using the Private Protocol protocol through xArm control box.

3.4.1.Private Protocol Communication Format

Private Protocol:

Modbus protocol is an application layer message transmission protocol, including three message types: ASCII, RTU, and TCP. The standard Modbus protocol physical layer interface includes RS232, RS422, RS485 and Ethernet interfaces, and adopts master / slave communication. Private Protocol Communication Process:

1.Establish a TCP connection

2.Prepare Modbus messages

3.Use the send command to send a message

4.Waiting for a response under the same connection

5.Use the recv command to read the message and complete a data exchange

6.When the communication task ends, close the TCP connection

Parameter:

Default TCP Port: 502 Protocol: 0x00 0x02

On the problem of users using communication protocols to organize data in big endian and little endian:

In this article, data analysis is big-endian analysis.

3.4.2.Read xArm Gripper Register

3.4.2.1. Register Function

Read Register
Request
MBTP Header	Transaction Identifier	2 Bytes	0x0001
	Protocol Identifier	2 Bytes	0x0002
	Length	2 Bytes	6+N*x2
	Unit Identifier	1 Byte	0x7C
Internal Use	Internal Use	1 Byte	0x09
Modbus RTU Data	Slave ID (Gripper)	1 Byte	0x08
	Function Code	1 Byte	0x03
	Register Starting Address	2 Bytes	Address
	Quantity of Registers	N*x2 Bytes	N*
Response
MBTP Header	Transaction Identifier	2 Bytes	0x0001
	Protocol Identifier	2 Bytes	0x0002
	Length	2 Bytes	6+N*x2
	Unit Identifier	1 Byte	0x7C
	Status Value	1 Byte	0x00
Internal Use	Internal Use	1 Byte	0x09
Modbus RTU Data	Slave ID	1 Byte	0x08
	Function Code	1 Byte	0x03
	Byte Count	1 Byte	N*x2
	Registers Value	N*x2 Bytes	Value

N* = Quantity of Registers Address = Register Starting Address

Resgister：

	Resgister Starting Address	Registers Value
Get Gripper status Register	0x0000	2 Bytes	Stop status: : 0x0000 Motion status: 0x0001Clipping status: 0x0010
Get Gripper position Register	0x0702	4bytes	0xFFFFFFFB-0x00000320
Get Gripper Error Register	0x000F	2 Bytes	An error occurs: all other return values indicate an error(except 0)No error occurred: 0x0000

3.4.2.2.Example

1.Get the xArm Gripper status

Get the xArm Gripper status
Request
MBTP Header	Transaction Identifier	2 Bytes	0x00，0x01
	Protocol Identifier	2 Bytes	0x00，0x02
	Length	2 Bytes	0x00，0x08
	Unit Identifier	1 Byte	0x7C
Internal Use	Internal Use	1 Byte	0x09
Modbus RTU Data	Slave ID (Gripper)	1 Byte	0x08
	Function Code	1 Byte	0x03
	Register Starting Address	2 Bytes	0x00，0x00
	Quantity of Registers	2 Bytes	0x00，0x01
Response
MBTP Header	Transaction Identifier	2 Bytes	0x00，0x01
	Protocol Identifier	2 Bytes	0x00，0x02
	Length	2 Bytes	0x00，0x08
	Unit Identifier	1 Byte	0x7C
	Status Value	1 Byte	0x00
Internal Use	Internal Use	1 Byte	0x09
Modbus RTU Data	Slave ID	1 Byte	0x08
	Function Code	1 Byte	0x03
	Byte Count	1 Byte	0x02
	Registers Value(Robotic arm is in motion status)	2 Bytes	0x00，0x01

2.Get the xArm Gripper position

Get the xArm Gripper position
Request
MBTP Header	Transaction Identifier	2 Bytes	0x00,0x01
	Protocol Identifier	2 Bytes	0x00,0x02
	Length	2 Bytes	0x00,0x08
	Unit Identifier	1 Byte	0x7C
Internal Use	Internal Use	1 Byte	0x09
Modbus RTU Data	Slave ID (Gripper)	1 Byte	0x08
	Function Code	1 Byte	0x03
	Register Starting Address	2 Bytes	0x07,0x02
	Quantity of Registers	2 Bytes	0x00,0x02
Response
MBTP Header	Transaction Identifier	2 Bytes	0x00,0x01
	Protocol Identifier	2 Bytes	0x00,0x02
	Length	2 Bytes	0x00,0x09
	Unit Identifier	1 Byte	0x7C
	Status Value	1 Byte	0x00
Parameters	Sate	1 Byte	0x00
Internal Use	Internal Use	1 Byte	0x09
Modbus RTU Data	Slave ID	1 Byte	0x08
	Function Code	1 Byte	0x03
	Byte Count	1 Byte	0x04
	Registers Value(position: 400)	4 Bytes	0x00,0x00,0x01,0x90

3.Get the xArm Gripper Error

Get the xArm Gripper Error
Request
MBTP Header	Transaction Identifier	2 Bytes	0x00,0x01
	Protocol Identifier	2 Bytes	0x00,0x02
	Length	2 Bytes	0x00,0x08
	Unit Identifier	1 Byte	0x7C
Internal Use	Internal Use	1 Byte	0x09
Modbus RTU Data	Slave ID (Gripper)	1 Byte	0x08
	Function Code	1 Byte	0x03
	Register Starting Address	2 Bytes	0x00,0x0F
	Quantity of Registers	2 Bytes	0x00,0x01
Response
MBTP Header	Transaction Identifier	2 Bytes	0x00,0x01
	Protocol Identifier	2 Bytes	0x00,0x02
	Length	2 Bytes	0x00,0x08
	Unit Identifier	1 Byte	0x7C
	Status Value	1 Byte	0x00
Parameters	Sate	1 Byte	0x00
Internal Use	Internal Use	1 Byte	0x09
Modbus RTU Data	Slave ID	1 Byte	0x08
	Function Code	1 Byte	0x03
	Byte Count	1 Byte	0x02
	Registers Value(No error occurred in the Gripper)	2 Bytes	0x00,0x00

3.4.3.Write xArm Gripper Register

3.4.3.1. Register Function

Write Register
Request
MBTP Header	Transaction Identifier	2 Bytes	0x00,0x01
	Protocol Identifier	2 Bytes	0x00,0x02
	Length	2 Bytes	9+N*x2
	Unit Identifier	1 Byte	0x7C
Internal Use	Internal Use	1 Byte	0x09
Modbus RTU Data	Slave ID (Gripper)	1 Byte	0x08
	Function Code	1 Byte	0x10
	Register Starting Address	2 Bytes	Address
	Quantity of Registers	2 Bytes	N*
	Byte Count	1 Byte	N*x2
	Registers Value	N*x2 Bytes	Value
Response
MBTP Header	Transaction Identifier	2 Bytes	0x00,0x01
	Protocol Identifier	2 Bytes	0x00,0x02
	Length	2 Bytes	0x00,0x09
	Unit Identifier	1 Byte	0x7C
	Status Value	1 Byte	0x00
Internal Use	Internal Use	1 Byte	0x09
Modbus RTU Data	Slave ID	1 Byte	0x08
	Function Code	1 Byte	0x10
	Register Starting Address	2 Bytes	Address
	Quantity of Registers	2 Bytes	N*

N* = Quantity of Registers

Address = Register Starting Address

Resgister:

	Resgister Starting Address	Registers Value
Set Gripper Mode Register	0x0101	2bytes	Position mode: 0x0000
Enable/Disable Gripper Register	0x0100	2 Bytes	Enable : 0x0001 Disable : 0x0000
Set Gripper Position Register	0x0700	4 Bytes	Open the Gripper : 0x0000 0x0082 Close the Gripper : 0x0000 0x0032
Set Position Speed Register	0x0303	2 Bytes	0x0100-0x0400 Unit : r/min

3.4.3.2.Example

1.Set xArm Gripper Mode

Set xArm Gripper Mode
Request
MBTP Header	Transaction Identifier	2 Bytes	0x00,0x01
	Protocol Identifier	2 Bytes	0x00,0x02
	Length	2 Bytes	0x00,0x0B
	Unit Identifier	1 Byte	0x7C
Internal Use	Internal Use	1 Byte	0x09
Modbus RTU Data	Slave ID (Gripper)	1 Byte	0x08
	Function Code	1 Byte	0x10
	Register Starting Address	2 Bytes	0x01,0x01
	Quantity of Registers	2 Bytes	0x00,0x01
	Byte Count	1 Byte	0x02
	Registers Value(Position mode)	2 Bytes	0x00,0x00
Response
MBTP Header	Transaction Identifier	2 Bytes	0x00,0x01
	Protocol Identifier	2 Bytes	0x00,0x02
	Length	2 Bytes	0x00,0x09
	Unit Identifier	1 Byte	0x7C
	Status Value	1 Byte	0x00
Parameters	Sate	1 Byte	0x00
Internal Use	Internal Use	1 Byte	0x09
Modbus RTU Data	Slave ID	1 Byte	0x08
	Function Code	1 Byte	0x10
	Register Starting Address	2 Bytes	0x01,0x01
	Quantity of Registers	2 Bytes	0x00,0x01

2.Enable/Disable xArm Gripper

Enable/Disable xArm Gripper
Request
MBTP Header	Transaction Identifier	2 Bytes	0x00,0x01
	Protocol Identifier	2 Bytes	0x00,0x02
	Length	2 Bytes	0x00,0x0B
	Unit Identifier	1 Byte	0x7C
Internal Use	Internal Use	1 Byte	0x09
Modbus RTU Data	Slave ID (Gripper)	1 Byte	0x08
	Function Code	1 Byte	0x10
	Register Starting Address	2 Bytes	0x01,0x00
	Quantity of Registers	2 Bytes	0x00,0x01
	Byte Count	1 Byte	0x02
	Registers Value	2 Bytes	0x00,0x01
Response
MBTP Header	Transaction Identifier	2 Bytes	0x00,0x01
	Protocol Identifier	2 Bytes	0x00,0x02
	Length	2 Bytes	0x00,0x09
	Unit Identifier	1 Byte	0x7C
	Status Value	1 Byte	0x00
Parameters	Sate	1 Byte	0x00
Internal Use	Internal Use	1 Byte	0x09
Modbus RTU Data	Slave ID	1 Byte	0x08
	Function Code	1 Byte	0x10
	Register Starting Address	2 Bytes	0x01,0x00
	Quantity of Registers	2 Bytes	0x00,0x01

3.Set xArm Gripper Speed

Set xArm Gripper Speed
Request
MBTP Header	Transaction Identifier	2 Bytes	0x00,0x01
	Protocol Identifier	2 Bytes	0x00,0x02
	Length	2 Bytes	0x00,0x0B
	Unit Identifier	1 Byte	0x7C
Internal Use	Internal Use	1 Byte	0x09
Modbus RTU Data	Slave ID (Gripper)	1 Byte	0x08
	Function Code	1 Byte	0x10
	Register Starting Address	2 Bytes	0x03,0x03
	Quantity of Registers	2 Bytes	0x00,0x01
	Byte Count	1 Byte	0x02
	Registers Value(1500r/min)	2 Bytes	0x05,0xDC
Response
MBTP Header	Transaction Identifier	2 Bytes	0x00,0x01
	Protocol Identifier	2 Bytes	0x00,0x02
	Length	2 Bytes	0x00,0x09
	Unit Identifier	1 Byte	0x7C
	Status Value	1 Byte	0x00
Parameters	Sate	1 Byte	0x00
Internal Use	Internal Use	1 Byte	0x09
Modbus RTU Data	Slave ID	1 Byte	0x08
	Function Code	1 Byte	0x10
	Register Starting Address	2 Bytes	0x03,0x03
	Quantity of Registers	2 Bytes	0x00,0x01

4.Set xArm Gripper Position

Set xArm Gripper Position
Request
MBTP Header	Transaction Identifier	2 Bytes	0x00，0x01
	Protocol Identifier	2 Bytes	0x00，0x02
	Length	2 Bytes	0x00，0x0D
	Unit Identifier	1 Byte	0x7C
Internal Use	Internal Use	1 Byte	0x09
Modbus RTU Data	Slave ID (Gripper)	1 Byte	0x08
	Function Code	1 Byte	0x10
	Register Starting Address	2 Bytes	0x07,0x00
	Quantity of Registers	2 Bytes	0x00,0x02
	Byte Count	1 Byte	0x04
	Registers Value(400)	4 Bytes	0x00,0x00,0x01,0x90
Response
MBTP Header	Transaction Identifier	2 Bytes	0x00,0x01
	Protocol Identifier	2 Bytes	0x00,0x02
	Length	2 Bytes	0x00,0x09
	Unit Identifier	1 Byte	0x7C
	Status Value	1 Byte	0x00
Parameters	Sate	1 Byte	0x00
Internal Use	Internal Use	1 Byte	0x09
Modbus RTU Data	Slave ID	1 Byte	0x08
	Function Code	1 Byte	0x10
	Register Starting Address	2 Bytes	0x07,0x00
	Quantity of Registers	2 Bytes	0x00,0x02

3.4.4.xArm Gripper Control Process

The complete process of controlling the motion of the xArm Gripper is as follows:

(1) Enable the Gripper

0x00, 0x01, 0x00, 0x02, 0x00, 0x0B, 0x7C, 0x09, 0x08, 0x10, 0x01, 0x00, 0x00, 0x01, 0x02, 0x00, 0x01

(2) Open the Gripper

0x00, 0x01, 0x00, 0x02, 0x00, 0x0D, 0x7C, 0x09, 0x08, 0x10, 0x07, 0x00, 0x00, 0x02, 0x04, 0x00, 0x00, 0x01, 0x90

(3) Close the Gripper

0x00, 0x01, 0x00, 0x02, 0x00, 0x0D, 0x7C, 0x09, 0x08, 0x10, 0x07, 0x00, 0x00, 0x02, 0x04, 0x00, 0x00, 0x00, 0x32

3.5.Use Modbus-RTU Communication Protocol to Control xArm Gripper

3.5.1.Modbus RTU Communication Format

The gripper defaults to the standard Modbus RTU protocol at a default baud rate is 2Mbps and the slave ID is 0x08. The currently supported function codes are: 0x03 / 0x10. In this article, data analysis is big-endian analysis.

Read Register
Request
Modbus RTU Data	Slave ID (Gripper)	1 Byte	0x08
	Function Code	1 Byte	0x03
	Register Starting Address	2 Bytes	Address
	Quantity of Register	2 Bytes	N*
	Modbus CRC16	2 Bytes	CRC*
Response
Modbus RTU Data	Slave ID	1 Byte	0x08
	Function Code	1 Byte	0x03
	Byte Count	1 Byte	N*x2
	Registers Value	N*x2 Bytes	Value
	Modbus CRC16	2 Bytes	CRC*

3.5.2.Read xArm Gripper Register

N* = Quantity of Registers

Address = Register Starting Address

CRC* = Cyclic Redundancy Check

Resgister：

	Resgister Starting Address	Register Value
Get Gripper status Register	0x0000	2 Bytes	Stop status: : 0x0000 Motion status: 0x0001Clipping status: 0x0010
Get Gripper position Register	0x0702	4bytes	0xFFFFFFFB-0x00000320
Get Gripper Error Register	0x000F	2 Bytes	An error occurs: all other return values indicate an error(except 0)No error occurred: 0x0000

3.5.3.Write xArm Gripper Register

Write Register
Request
Modbus RTU Data	Slave ID (Gripper)	1 Byte	0x08
	Function Code	1 Byte	0x10
	Register Starting Address	2 Bytes	Address
	Quantity of Register	2 Bytes	N*
	Byte Count	1 Byte	N*x2
	Registers Value	N*x2 Bytes	Value
	Modbus CRC16	2 Bytes	CRC*
Response
Modbus RTU Data	Slave ID	1 Byte	0x08
	Function Code	1 Byte	0x10
	Register Starting Address	2 Bytes	Address
	Quantity of Registers	2 Bytes	N*
	Modbus CRC16	2 Bytes	CRC*

N* = Quantity of Registers

Address = Register Starting Address

CRC* = Cyclic Redundancy Check

Resgister:

	Resgister Starting Address	Register Value
Enable/Disable Gripper Register	0x0100	2 Bytes	Enable : 0x0001 Disable : 0x0000
Set Gripper Position Register	0x0700	4 Bytes	Open the Gripper: 0x0000 0x0082 Close the Gripper: 0x0000 0x0032
Set Position Speed Register	0x0303	2 Bytes	0x0100-0x0400 Unit: r/min
Set Gripper Mode Register	0x0101	2bytes	Position mode: 0x0000

3.5.4.Modbus RTU Example

This section demonstrates the example given in the Control Logic section when programmed using the Modbus RTU protocol.

Step1：Set xArm Gripper Mode

Set xArm Gripper Mode
Request
Modbus RTU Data	Slave ID (Gripper)	1 Byte	0x08
	Function Code	1 Byte	0x10
	Register Starting Address	2 Bytes	0x01,0x01
	Quantity of Registers	2 Bytes	0x00,0x01
	Byte Count	1 Byte	0x02
	Registers Value	2 Bytes	0x00,0x00
	Modbus CRC16	2 Bytes	0xDD,0x11
Response
Modbus RTU Data	Slave ID	1 Byte	0x08
	Function Code	1 Byte	0x10
	Register Starting Address	2 Bytes	0x01,0x01
	Quantity of Registers	2 Bytes	0x00,0x01
	Modbus CRC16	2 Bytes	0x51,0x6C

Step2：Enable xArm Gripper

Enable xArm Gripper
Request
Modbus RTU Data	Slave ID (Gripper)	1 Byte	0x08
	Function Code	1 Byte	0x10
	Register Starting Address	2 Bytes	0x01,0x00
	Quantity of Registers	2 Bytes	0x00,0x01
	Byte Count	1 Byte	0x02
	Registers Value	2 Bytes	0x00,0x01
	Modbus CRC16	2 Bytes	0x1D,0x00
Response
Modbus RTU Data	Slave ID	1 Byte	0x08
	Function Code	1 Byte	0x10
	Register Starting Address	2 Bytes	0x01,0x00
	Quantity of Registers	2 Bytes	0x00,0x01
	Modbus CRC16	2 Bytes	0x00,0xAC

Step3:Set xArm Gripper Speed

Set xArm Gripper Speed
Request
Modbus RTU Data	Slave ID (Gripper)	1 Byte	0x08
	Function Code	1 Byte	0x10
	Register Starting Address	2 Bytes	0x03,0x03
	Quantity of Registers	2 Bytes	0x00,0x01
	Byte Count	1 Byte	0x02
	Registers Value(1500r/min)	2 Bytes	0x05,0xDC
	Modbus CRC16	2 Bytes	0xFD,0xFA
Response
Modbus RTU Data	Slave ID	1 Byte	0x08
	Function Code	1 Byte	0x10
	Register Starting Address	2 Bytes	0x03,0x03
	Quantity of Registers	2 Bytes	0x00,0x01
	Modbus CRC16	2 Bytes	0xF1,0x14

Step4:Set xArm Gripper Position

Set xArm Gripper Position
Request
Modbus RTU Data	Slave ID (Gripper)	1 Byte	0x08
	Function Code	1 Byte	0x10
	Register Starting Address	2 Bytes	0x07,0x00
	Quantity of Registers	2 Bytes	0x00,0x02
	Byte Count	1 Byte	0x04
	Registers Value(position：400)	4 Bytes	0x00,0x00,0x01,0x90
	Modbus CRC16	2 Bytes	0xFA，0xFF
Response
Modbus RTU Data	Slave ID	1 Byte	0x08
	Function Code	1 Byte	0x10
	Register Starting Address	2 Bytes	0x07,0x00
	Quantity of Registers	2 Bytes	0x00,0x02
	Modbus CRC16	2 Bytes	0x40,0x25