2F-85 & 2F-140 - Instruction Manual
4.7.ModbusRTU Communication
The gripper can be controlled by ModbusRTU directly with RS485-RS232 using the ACC-ADT-RS232-RS485, or over USB using the
ACC-ADT-USB-RS485. Thissection is intended to provide guidelines for setting up a Modbus master 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_
02.pdf.
For debugging purposes, the reader is also invited to download one of many free Modbusscanners such as the CASModbus
Scanner from Chipkin Automation Systems available at: http://www.store.chipkin.com/products/tools/cas-modbus-scanner.
Info
Modbus RTU is a communication protocol based on a Big Endian byte order. Therefore, the 16-bit register addresses
are transmitted with the most significant byte first. However, the data port is in the case of Robotiq products based on
the Little Endian byte order. As such, the data parts of Modbus RTU messages are sent with the less significant byte first.
Tip
Modbus RTU specification and details can be found at www.modbus.org.
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