General Description; Rs485; Modbus Protocol Description; Protocol Application - INVT DA180-S2R8SG0 Operation Manual

DA180 series basic AC servo drive

8.1 General description

DA180 servo drive provides RS485 and CANopen interfaces to communicate with the upper
computer NC or PLC. The NC or PLC can implement asynchronous serial half-duplex communication
with 31 servo drivers simultaneously through the RS485 interface or with 127 servo drivers
simultaneously through the CAN interface to:

Read servo drive function parameters

Monitor drive servo working status

Form a multi-shaft control system
DA180 servo drive provides the USB and CANopen interfaces to communicate with the PC. Thus, the
PC uses either of the interfaces to calibrate the parameter settings, monitor status, and read data
from and write data to the servo driver.

8.2 RS485

DA180 servo drive provides the RS485 communication interface, which uses the standard Modbus
communication protocol to implement master/slave communication. You can implement integrated
control on the PC, PLC, or upper computer to meet specific application requirements. Integrated
control includes setting servo drive control commands, running frequency, function codes, and
working status, and monitoring fault information.

8.2.1 Modbus protocol description

The Modbus serial communication protocol defines the frame content and formats asynchronously
transferred. The formats include those for master-node polling, broadcast frames, and slave-node
response frames. The content of a frame sent from the master node includes the slave-device
address (or broadcast address), execution command, data, and error checking. The response from a
slave node is structured similarly to a frame sent from the master node. The response content
includes action confirmation, data returning, and error checking. If a slave node encountered an error
in receiving frames or failed completing the action required by the master node, the slave node sends
back a fault frame as response to the master node.

8.2.2 Protocol application

DA180 servo drive uses the asynchronous serial master/slave Modbus communication protocol,
which indicates only one device (that is, master node) in the network can establish protocols (called
"queries/commands"). The other devices (that is, slave nodes) can only provide data response to or
react according to the "queries/commands" from the master node. The master node herein indicates
the PC, industrial control device, or PLC, while slave nodes indicate DA180 servo drive or control
devices with the same communication protocol. The master node can not only communicate with one
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Communication