Athena C10 line Manual de Instruções descarregar pdf (Página 11)

Example: Request for slave 17 to read bits 0004 to 0015.

ADDR

FUNC

DATA

start

Addr HI

DATA

start

Addr LO

DATA

bit #

DATA

bit #

CRC

11 01 00 03 00 0C CE 9F

Answer

In addition to the address of the slave and the function code (01), the

message comprises a character containing the number of data bytes and

the characters containing data. The data are compacted, so one byte

contains the status of 8 bits, the least significant bit of the first byte must

contain the bit corresponding to the starting address and so on. If the

number of bits to be read is not a multiple of 8, the last character must be

completed with zeros in the most significant bits.

Example: Answer to the request indicated above.

ADDR

FUNC

DATA

Byte

Count

DATA

bit

04..11

DATA

bit

12..15

CRC

11 01 02 CD 0B 6D 68

3.2 Read Input Status (02)

This function works in exactly the same way as the previous one.

3.3 Read Output Registers (03)

This function is used for requesting the value of 16-bit (word) registers

containing numeric variables. Broadcast mode is not allowed.

Question

In addition to the address of the slave and the function code (03), the

message contains the starting address expressed in two bytes and the

number of words to be read, also occupying two bytes. The maximum

number of words that may be read is 125. Address numbering starts from

zero (word1 = 0) for MODBUS, or one (word1 = 1) for JBUS.

Example: Request for slave 25 to read registers 069 to 0071.

ADDR

FUNC

DATA

start

Addr HI

DATA

start

Addr LO

DATA

word #

DATA

word #

CRC

19 03 00 44 00 03 46 06

Answer

In addition to the address of the slave and the function code (03), the

message comprises a character containing the number of data bytes and

the characters containing data. The registers require two bytes each, the

first of which contains the most significant byte.

Example: Answer to the request indicated above.

ADDR

FUNC

DATA

Byte

Count

DATA

word

69 HI

DATA

word

69 LO

DATA

word

70 HI

DATA

word

70 LO

DATA

word

71 HI

DATA

word

71 LO

CRC

19 03 06 02 2B 00 00 00 64 AF 7A

3.4 Read Input Registers (04)

This function works in exactly the same way as the previous one.

1 2 ... 6 7 8 9 10 11 12 13 14 15 16 ... 106 107

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Athena C10 line Manual de Instruções Página 11

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