Modbus-Rtu Protocol - Toshiba TOSVERT VF-FS1 Instruction Manual

Communications function
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5. MODBUS-RTU protocol

The MODBUS-RTU protocol of VF-FS1 supports only part of the MODBUS-RTU protocol.
All data will be binary codes.
■ Parameter Setting
• Protocol Selection (
Select "MODBUS - RTU protocol (
"TOSHIBA Inverter Protocol" (
shipment setting. (See "3. Communication protocol".)
• Inverter Number (
Inverter numbers. 0 to 247 can be specified in MODBUS-RTU. "0" is allocated to broadcast com-
munication (no return). Set between 1 and 247.
<Related Parameter: Change and set as necessary>
■ Timing of Message from Host
MODBUS-RTU sends and receives binary data without a frame synchronization header character
and defines the frame synchronizing system to recognize the start of a frame by no-data time.
MODBUS-RTU initializes frame information and decides the data that is first received subsequently
as the first byte of a frame if data is not communicated within a time for 3.5 bytes, including the start
and stop bits, at the transmission speed of the on-going communication while standing by for data
reception. If a frame is being received before no-data time for 3.5 bytes, this frame will be aborted.
Be sure to provide more than 3.5 bytes for data send interval.
Send data so that the time between characters will not be spaced for more than 1.5 bytes. Other-
wise, MODBUS-RTU will sometimes recognize it as a start of data.
In the case of data to other stations, messages from the host and responses from other stations are
also received. A wait time for 3.5 bytes is needed before starting transmission after own station
completes reception when sending a response to recognize a frame start at this time.
)
)
: Communication baud rate
: Parity
: Communication error trip time
=
) in the communication selection parameters.
= ) is set for communication protocol selection in initial
25
E6581393

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