3-Finger Adaptive Robot Gripper Instruction Manual
4.7 MODBUS RTU communication protocol
The Robotiq 3-Finger Gripper can be controlled via RS485 or RS232 by using the Modbus RTU protocol. This section is intended to provide guidelines
for setting up a Modbus scanner that will adequately communicate with the Gripper.
For a general introduction to Modbus RTU and for details regarding the CRC algorithm, the reader is invited to read the Modbus over serial line
specification and implementation guide available at: http://www.modbus.org/docs/Modbus_over_serial_line_V1.pdf.
For debugging purposes, the reader is invited to download one of many free Modbus scanners, such as the
CAS Modbus Scanner
from
Chipkin
Automation Systems
, which is available at: http://www.chipkin.com/cas-modbus-scanner.
Caution
The Adaptive Gripper register values are updated at a 100Hz frequency. It is therefore recommended to send commands with a minimum
interval delay of 10ms. Note that the updated frequency may drop under some conditions where the response time would be longer.
4.7.1 Connection setup
The following table describes the connection requirements for controlling the Robotiq 3-Finger Gripper using the Modbus RTU protocol.
PROPRIETY
VALUE
Physical Interface
RS485-RS232
Baud Rate
115,200 bps
Data Bits
8
Stop Bit
1
Parity
None
Number Notation
Hexadecimal
Supported Functions
Read Holding Registers (FC03)
Preset Single Register (FC06)
Preset Multiple Registers (FC16)
Exception Responses
Not supported
Slave ID
0x0009 (9)
Robot Output / Gripper Input First Register
0x03E8 (1000)
Robot Input / Gripper Output First Register
0x07D0 (2000)
Each register (word - 16 bits) of the Modbus RTU protocol is composed of 2 registers (bytes – 8 bits) from the Robotiq 3-Finger Gripper. The first
Gripper output Modbus register (0x07D0) is composed from the first 2 Robotiq 3-Finger Adaptive Robot Gripper registers (byte 0 and byte 1).
4.7.2 Read holding registers (FC03)
Function code 03 (FC03) is used for reading the status of the Gripper (robot input). Examples of such data are Gripper Status, Object Status, Finger
Position, etc.
Ex: This message asks for register 0x07D0 (2000) and register 0x07D1 (2001) which contains Gripper Status, Object Detection, Fault Status and
Position Request Echo.
Request is:
09 03 07 D0 00 02 C5 CE
where
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