Modbus Rtu Transmission Format - Toshiba Tosvert VF-S15 Series Instruction Manual

5.1.Modbus RTU transmission format

Modbus RTU sends and receives binary data without a frame-synchronizing start code and defines
the blank time to recognize the start of a frame. Modbus RTU decides the data that is first received
subsequently as the first byte of a frame after a blank time for 3.5 bytes at the on-going communica-
tion speed.
Inverter
(3.5bytes
No.
Blank)
1byte
1) Inverter No. (1 byte)
2) Command (1 byte)
Command
Decimal Hex
03 03H
06 06H
16 10H
16 10H
23 17H
43 2BH
3) Data (variable ｌength)
4) CRC (2 bytes)
Inverter
(3.5bytes No.
Blank)
1byte
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【Request format / Positive response】
Command
1byte
: Specify an inverter number between 0 and 247 (00H to F7H).
Command processing will be executed only broadcast communication "0" and with
those inverters that match set inverter numbers. Data will not be returned if "0"
(broadcast communication) and inverter numbers do not match. Don't use the
number between 248 and 255(F8H to FFH) for inverter option and shipment test.
: Set the command. Refer to section 5.1.7 from 5.1.1
Function
Read
Block read
Write
Block write
Block write and read
Identification
: Set the data requested by command.
: Set generation results of CRC in the order of low to high numbers. For the method
to generate CRC, see "5.2. CRC Generation". Note that the setting sequence is
reversal to that of others.
【Negative response】
Command
Requested command
+ 80H
Data
variable length
Reference
Read the data with the specified
communication number.
Block read communication (Indirect)
Block read communication (Direct)
Write the data with the specified
communication number.
(RAM and EEPROM).
Block write communication (Indirect)
Block write and read communication
(Indirect)
Reads the Inverter information
(manufacture , type format , software
version)
Error code
See "5.3. Error codes".
25
E6581913
CRC16
(3.5bytes
low high
Blank)
１byte １byte
Remarks
5.1.1
5.1.2
5.1.3
5.1.4.1
5.1.4.2
5.1.5
5.1.6
5.1.7
CRC16
(3.5bytes
low high
１byte １byte
Blank)