ENGLISH
Technical information for Modbus connections
COMMUNICATION PROTOCOL
The protocol used is MODBUS RTU mode with the following characteristics:
RS-485 (2 wire). Maximum number of elements on the bus: 32 (1 master + 31 slaves).
- Communication speed: 9600 baud.
- Data format:
- 8 bits.
- No parity.
- 1 stop bit.
- 16 bit registers (2 bytes).
Variable format: High Word First [H / L].
- CRC according to polynomial x16 + x15 + x2 + 1.
Note: It is recommended to retry communications. Timeout: 1sec.
Note: Minimum recommended Wait To Send time: 100ms.
READING OF RECORDS
For reading registers it is possible to use command codes 3 or 4 with the following message structure:
Slave No. (1 byte) - Code (03 or 04) (1 byte) - Address of the 1st register to read (00-XX) (2 bytes) - No. of
registers to read (00-YY) (2 bytes) - CRC16 (2 bytes)
Maximum number of records to read in the same message = 61 (from record 0 to record 60)
The regulator's reply has the following message structure:
Slave number (1 byte) - Code (03 or 04) (1 byte) - Number of data bytes (XX) (1 byte) - Data (AA-BB-CC-DD ...)
(2 bytes for each register) - CRC16 (2 bytes) Number of data bytes = 2 * Number of records to read.
RECORD WRITING
For writing registers, command code 6 is used with the following message structure:
Slave number (1 byte) - Code (06) (1 byte) - Address of the register to write (00-XX) (2 bytes) - Data to write to
the register (AA-BB) (2 bytes) - CRC16 (2 bytes)
The regulator's reply has the following message structure:
Slave number (1 byte) - Code (06) (1 byte) - Address of the written register (00-XX) (2 bytes) - Data written in
the register (AA-BB) (2 bytes) - CRC16 (2 bytes)
MISTAKES
If a code other than the indicated read or write code is used, the response received is:
Slave number - OR code 80Hex - Error code (1) - CRC16 (2 bytes)
If you try to read or write access to a record with a non-existent address, the response received is:
Slave number - OR code 80Hex - Error code (2) - CRC16 (2 bytes)
If you try to write to a read-only record or try to write an illegal value to a record, the response you receive is:
Slave number - OR code 80Hex - Error code (3) - CRC16 (2 bytes)
RECORD MAP
The unused bits in the following registers are 0.
Note: In some communication programs, the first word address is configured as 400001, so register 0 of the
controller corresponds to the word
address 400001. In summary, the word address to which each register of the controller corresponds is
calculated adding 1 to the record number of the record map described below.
Device ID record
Record 0: Hardware code [read-only].
- The controller responds with the hardware code (143) as a 16-bit binary sentinel point. Hardware TX143: 143.
Read / write registers
Record 1: Communications address [read / write].
- The value that is sent is the value of the address (1 to 240) in 16-bit binary. Default value: 1 [1].
If the controller is connected to a serial communications network, it is not possible to configure any equipment
on the network at address 245,
since the Regulator also responds to that direction.
BROADCAST ADDRESS: Address 250 (the controller receives the communication, but does not respond). All
writing records are broadcast.
Record 2: Operation status on / off (manual mode) [read / write].
0: Off.
1: On.
Default value: 0 [Off].
= 240 (0xF0): Default values.
= 255 (0xFF): Reset.
Record 3: Fan speed setpoint [read / write].
The value that is sent is the speed value (0% to 100%) in 16-bit binary.
Default value: 70 [70%: Fan on].
Record 4: Set fan speed period 1 (time programming) [read / write].
The value that is sent is the speed value (0% to 100%) in 16-bit binary.
Default value: 50 [50%: Fan on].
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