Calpeda NCE HQ2 Instrucciones De Uso página 159

18.3.1 Slave address
Each slave has its 8-bit address. The factory default address of the hot water
circulation pump is 0x01. The slave addresses in the same network cannot be
duplicated. Except for the broadcast address, the slave only acknowledges and
responds to messages with the same ID as itself. The communication protocol
defines a broadcast address: 0xFF.
Slave address Command
Only when the slave address (1-247) corresponds, execute the command and
0x01 to 0xF7
reply to the master.
All slaves receive and execute commands and reply to the master. For
0xFF
one-to-one configuration control.
18.3.2 Supported command codes
Code Command
0x03 Read holding register
0x04 Read input register
0x06 Write a single register
18.3.3 Data
Different instruction data word definitions are also different. For details, see Section
5.4 UART Command Detailed Explanation and Section 5.5 Register Value Range.
18.3.4 CRC check
Redundant cyclic code CRC16 (MODBUS), including 2 bytes, when sending, the
low byte comes first, and the high byte follows.
18.4 UART Detailed command
18.4.1 Command code = 0x03 (read holding register)
Master to slave:
Slave Command
address code
(1 byte) (0x03)
Slave to master (reply):
Slave Command
address code
(1 byte) (0x03)
18.4.2 Command code = 0x04 (read input register)
Master to slave
Slave Command
address code
(1 byte) (0x04)
First holding register
address (2 bytes, high
byte first)
Total number First
of data bytes register
(1 byte) data
Input register start
address (2 bytes, high
byte first)
158
Number of Check CRC
registers read
(2 bytes)
(2 bytes)
. . . Nth register CRC check
data (2 bytes)
Number of
CRC check
registers read (2 bytes)
(2 bytes)
GB