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7 MODBUS communication protocol
7.1 Communication protocol
7.1.1 Protocol content
The serial communication protocol defines the information content and the use of
serial communication transmissionformat, including: Host polling (or broadcast) format;
host encoding method, including: action-requiring function code, data transfer & error
correction; mortem response from the slave is the same structure, including: action
confirmation, return data & error checking, etc. If an error occurs when the slave receives
information, or host requested action can not be completed, it will organize a fault as a
feedback information to the host.
Application mode:
Inverter joins RS232/RS485 fieldbus compatible master-slavery PC/PLC control
network.
Fieldbus structure:
(1)Interface mode
RS232/RS485 hardware interface
(2)Transmission mode
Asynchronous serial, half-duplex transmission mode.At the same time there can be
only one master slave transmit data while the other can only receive data. Data on the
serial asynchronous communication, is in the form of packets sent frame by frame.
(3)Topological structure:
Single master multi-slave system. Slave address setting range is 1 to 247, 0 is broadcast
communication address. Network slave address must be unique.
7.1.2 Protocol
DLB1 series inverter is an asynchronous serial communication Modbus master-slave
communication protocol. Only one device on the network (host) can establish an
agreement (called "query/command"). Other devices (slave) can onlyrespond to the host's
"query/command"by providing data, or take actions according to the host's
"query/command". The host can be personal computer (PC), industrial control equipment
or a programmable logic controller (PLC); slave is DLB1 inverter. Host can communicate to
an independent slave machine, or can broadcast information to all slaves. For independent
host "query/command", slave returns information (known as the response).For broadcast
information, slave no need to send response to the host.
DLB1 series inverter Modbus data communication protocol format is as follows: using
RTU mode, sending a message must start with an at least 3.5 characters interval time.
Transmittable characters are hexadecimal 0 ... 9, A... F. Network equipment keeps on
detectingnetwork bus, including interval time. When the first domain (address field) is
Summary of Contents for DLB1-0D40S2G
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Page 15: ...15 Graph 2 922 400KW inverter wiring diagram...
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