Alpha 6000S series - Display Control Parameters (Group PC)

Chapter 5 Detailed Function Introductions
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5.12 MODBUS Communication (Group Pb)
The series of frequency inverters can conduct the serial communication via the MODBUS communication protocol
and the programmable logic controller (PLC). MODBUS consists of a controlling PLC and 1-31 frequency inverters
of this series. The signal transmission between the controlling and the controlled is always started and done by the
controlling, while the controlled responds to the signal.
The controlling frequency inverter conducts the signal transmission with one controlled frequency inverter once. The
controlled frequency inverter will perform its function and respond to the controlling inverter after receiving the
command sent by the controlling inverter.
 Communication Specification
Interface: RS-485 Synchronization Manner: half-duplex asynchronous
 Transmission Parameters:
Baud rate: Selectable from 1200, 2400, 4800, 9600, 19200, 38400 BPS (parameter Pb.00)
Data length: fixed at 8 bits
Parity: even parity/no parity/odd parity selectable (parameter Pb.02)
Stop bit: fixed at 1 bit
Protocol: In accordance with MODBUS
Maximum number of units to be connected: 31 units
 Data sent/received through communication: data sent/received through communication include the operation
command, frequency giving, fault content, invert state and setting & reading of function parameters. The
monitoring content and the reading &writing function parameters can be read through starting up by default;
Pb.00 Baud rate selection Setting range:0~5 [3]
0: 1200 bps 1: 2400 bps
2: 4800 bps 3: 9600 bps
4: 19200 bps 5: 38400 bps
Pb.01 Address of the Inverter Setting Range: 0~31 [1]
Notes:
 The address of the inverter set cannot be the same with the addresses of other controlled devices connected to
the same transmission line.
Pb.02 Even-odd Check Selection Setting Range: 0~2 [0]
0: Even Check
2: No Check
1:Odd Check
Pb.03 Communication Timeout Check Time Setting Range: 0~100.0s [0.0s]
Notes:
 0:there is no timeout check
 Non-0: there is the timeout check. The system will check the communication state at the interval of the Pb.03
setting value. If there is no normal data receive or sent, the system will report the external communication
fault (EF0) and stop the machine; the fault should be cleared manually;
 Tips:
If only abnormal data are received during the timeout check, they will not be used as the base for being in
communication and fault will be reported;
Pb.04 Response delay time Setting range: 0~500ms [5ms]
Notes:
 It refers to the time from inverter receiving the host PC command to returning response frame to it.