TOSHIBA VF-AS3 inverter RS485 communication function

(4) Broadcast communication

Only supports write commands (W/P), does not support read commands, suitable for batch configuration of all devices.

ASCII mode: INV-NO is set to "* *" (such as (* * PFA011770) CR), only the device numbered 00 responds, and other devices do not respond when executing commands.

Binary mode: INV-NO is set to FFH, and only the device numbered 00 responds to avoid bus conflicts.

2. MODBUS-RTU protocol (compatible with third-party devices)

Only supports MODBUS-RTU subset (binary transmission), does not support ASCII mode, suitable for networking with third-party PLCs, touch screens, and other devices. The core instructions are as follows:

Instruction code (Hex) function description applicable scene frame format (computer → frequency converter)

03H Read Keep Register reads one or more parameters (indirect read ≤ 5, direct read ≤ 8) inverter number+03H+communication number (high-order)+read word count (high-order)+CRC16

Write a single hold register in 06H and write one parameter (such as frequency instruction, run command): frequency converter number+06H+communication number (high-order first)+write data (high-order first)+CRC16

10H write multiple hold registers, write 2 or more parameters (such as block write preset parameters), inverter number+10H+communication number (high-order)+write word count (high-order)+data byte count+write data+CRC16

Write and read multiple registers in 17H, simultaneously write parameters+read parameters (such as write frequency+read output current), inverter number+17H+read communication number+read word count+write communication number+write word count+data byte count+write data+CRC16

2BH reads model information, manufacturer, model, and version (such as "TOSHIBA" and "VFAS3-2037P"), inverter number+2BH+MEI type (0EH)+equipment code+object code+CRC16

(1) CRC16 Calculation Rule (Required)

The CRC16 of MODBUS-RTU is a 16 bit checksum, and the calculation steps are as follows:

Initialize the CRC register to FFFFH;

XOR the data byte by byte with the CRC register;

Shift each byte by 1 bit to the left. If the lowest bit is 1, XOR the CRC register with polynomial A001H;

Repeat step 3 8 times to process all bytes;

The final CRC value is stored at the end of the frame with "low bits first, high bits second".

Example: The CRC16 of the command "01 03 FD 00 00 01" is B5A6H, and the complete command is "01 03 FD 00 01 B5 A6".

(2) Example: Read output frequency (communication number FD00)

Inverter parameters: Number 1 (01H), baud rate 19200bps, even parity.

Computer command: 01 03 FD 00 00 01 B5 A6 (01=number, 03=read, FD00=communication number, 0001=read 1 parameter).

Inverter response: 01 03 02 17 70 B6 50 (02=number of data bytes, 1770H=6000 → 60.00Hz, B650=CRC16).

Core function: master-slave communication between frequency converters

Without the need for an upper computer, synchronous control of one master and multiple slaves can be achieved through the RS485 bus, which only supports Toshiba inverter protocol. The main station sends S command (53H), and the slave station does not respond when receiving commands, avoiding bus conflicts.

1. Master slave parameter configuration (key parameters)

Example Setting of Character Core Parameter Configuration Options (45Hz Output from the Station)

Master station [F806]/[F826] (master-slave mode) 3=frequency command, 4=output frequency, 5=torque command, 6=output torque [F826]=3 (frequency command)

Main station [F805]/[F825] (transmission waiting time) 0.00-2.00s (default 0.00s) 0.01s (to avoid the main station sending too fast)

Slave station [F806]/[F826] (master-slave mode) 0=0Hz in case of fault, 1=continue operation in case of fault, 2=emergency stop in case of fault [F826]=0 (fail safe)

From station [F823] (communication timeout) 0.1-100.0s (default 0.0s disabled) 1.0s (tripped when cable disconnected)

Slave [FMOd] (frequency command source) 21=Connector1, 22=Connector2 22 (same interface as the master station)

Slave [FH] (maximum frequency) 0.0-400.0Hz 90.0Hz (target maximum frequency)

2. Speed proportional control logic

The frequency of the slave station is calculated according to the proportion of the master station's instructions, and supports two modes: "no correction" and "two-point correction":

(1) No calibration mode (F810=0)

Calculation formula: Slave frequency (Hz)=(Master command value (%) x Slave maximum frequency (Hz))/10000

Main station command value: 1%=100 (e.g. 50%=5000), main station frequency command=(actual frequency of main station x 10000)/maximum frequency of main station.

Example: The maximum frequency of the main station is 60Hz, and the actual output is 30Hz → Main station command=(30 × 10000)/60=5000 (50%); The maximum frequency of the slave station is 90Hz → the slave station frequency=(5000 × 90)/10000=45Hz.

(2) Two point correction mode ([F810]=1, non-linear ratio)

Preset two parameters: [F811]=Point 1 command value (%), [F812]=Point 1 frequency (Hz); [F813]=Point 2 command value (%), [F814]=Point 2 frequency (Hz).

Calculation formula: Slave frequency=Point 1 frequency+(Main station instruction - Point 1 instruction) × (Point 2 frequency - Point 1 frequency)/(Point 2 instruction - Point 1 instruction)