TOSHIBA VF-AS3 inverter RS485 communication function

(3) 2-wire and 4-wire wiring examples

2-wire system (default, recommended): A+(4-pin) interconnection, B - (5-pin) interconnection, SG (8-pin) interconnection for all devices, with 120 Ω terminal resistors connected at both ends of the bus and pull-down resistors connected at each node.

4-wire system (requires [F829]=1): The TXA+(3-pin)/TXB - (6-pin) of the master station is connected to the RXA+(4-pin)/RXB - (5-pin) of all slave stations, and the slave stations have no transmit pin (no response). The rest is the same as the 2-wire system, suitable for master-slave unidirectional communication and high reliability scenarios.

3. Transmission specification parameters

Transmission parameter support options default values note

Half duplex transmission method - can only receive or send data at the same time to avoid conflicts

Synchronization mode start and end synchronization - identify the beginning and end of frames by "3.5 byte blank time" (9600bps ≈ 4ms, 19200bps ≈ 2ms, 38400bps ≈ 1ms)

The baud rate is 9600bps/19200bps/38400bps. After modifying 19200bps, it needs to be powered off and reset to take effect. All bus devices must be consistent

No parity check/even parity check/odd parity check. After modifying the parity check, it needs to be powered off and reset to take effect. It is recommended to use even parity check (with strong anti-interference ability)

8-bit data bit (ASCII: JIS X0201; Binary/MODBUS: fixed 8-bit) - no options, non modifiable

Stop bit reception: 1 bit; Sending: 2 bits - compatible with upper computer 1/1.5/2 bit stop bit settings, no adaptation required

Error detection Toshiba protocol: checksum (optional); MODBUS-RTU: CRC16 (required) - When verifying an error, the frequency converter does not respond, and the upper computer needs to resend it

Detailed explanation of communication protocol (dual protocol support)

VF-AS3 supports two communication protocols, which can be switched through parameters [F807] (Connector1)/[F827] (Connector2). The default is the "Toshiba Inverter Protocol", and two protocols (different interfaces) can be enabled simultaneously.

1. Toshiba inverter protocol (native protocol, with the most comprehensive functions)

Supports ASCII, Binary, and block communication modes, accessing inverter parameters through a "communication number" (4-digit hexadecimal). The command set covers read, write, and inter inverter communication, making it suitable for Toshiba device networking.

(1) ASCII mode (suitable for PC/PLC, with strong readability)

Frame format (computer → frequency converter): (INV-NO CMD communication number DATA&SUM) CR

Initial code: "(" (28H), final code: ")" (29H)+CR (0DH), cannot be omitted.

INV-NO: Inverter number (2-digit ASCII, 00-99, "* *" represents broadcast).

CMD: Command code (R=Read, W=Write RAM+EEPROM, P=Write RAM, G=Read (2-wire system specific)).

Communication number: 4-digit hexadecimal (e.g. FD00=output frequency, FA01=frequency command).

SUM: checksum (2-digit ASCII, optional), calculated as "the last two digits of the sum of all ASCII codes between the header and&".

Example: Set the frequency to 60Hz (communication number FA01, 60Hz=1770H)

Command: (00PFA011770) CR (00=inverter number, P=write to RAM, 1770=hexadecimal corresponding to 60Hz).

Response: (00PFA011770) CR (The frequency converter returns the same command, confirming successful writing).

(2) Binary mode (suitable for microcontrollers/embedded systems, high transmission efficiency)

Frame format (computer → frequency converter):/INV-NO CMD communication number DATA SUM

Header code: "/" (2FH), no tail code, SUM (1 byte) is required.

INV-NO: Inverter number (1-byte hexadecimal, 00H-3FH, FFH=broadcast).

CMD: Command code (52H=R, 57H=W, 50H=P, 53H=S (between frequency converters)).

Communication number: 2-byte hexadecimal (high-order, such as FD00=output frequency).

SUM: checksum (1 byte), calculated as the last 8 bits of the sum of all bytes from the header to DATA.

Example: Read output frequency (communication number FD00)

Command: 2F 52 FD 00 82 (2F=/, 52=R, FD00=communication number, 82=SUM).

Response: 2F 52 FD 00 17 70 05 (1770H=6000 → 60.00Hz, 05=response SUM).

(3) Block communication mode (efficient batch read/write)

Core advantage: A single communication can simultaneously write 2 parameters and read 5 parameters, reducing the number of communication times and suitable for batch configuration or centralized monitoring scenarios.

Parameter preset: You need to first set the "block write parameters" (such as FA00=run command, FA01=frequency command) through [F870]/[F871], and set the "block read parameters" (such as FD00=output frequency, FD03=output current) through [F875] - [F879].

Frame format: Computer sends X command (58H), frequency converter sends Y command (59H), example:

Computer command: 2F 58 02 05 C4 00 17 70 D9 (02=write 2 parameters, 05=read 5 parameters, C400=forward command, 1770=60Hz).

Inverter response: 2F 59 05 00 64 00 17 70 1A 8A 24 FD 00 3D (returns 5 read parameter results, 64=100 → 60Hz, 1A8A=6794 → 67.94% current, etc.).