Table des Matières
Publicité
Request
Controller address
Function
Data address (MSB)
Data address (LSB)
word number (MSB)
word number (LSB)
CRC16 (MSB)
CRC16 (LSB)
In this example the controller has a MODBUS address as 1 and required data, firmware release is 1.02, coded as 0x0102. Furthermore MSB
and LSB means respectively Most Significant Byte e Least Significant Byte.
Error control
In case o fan error due to:
• not supported function
• wrong data address
• wrong data length
reply message will be a MODBUS exception.
Reply will contain as function code the request core in OR bit a bit with 0x80 and a additional byte with error description.
Two error codes are supported:
• 0x01
Illegal function
• 0x02
Illegal data address
Refer ot protocol description in the already mentioned references for reply format protocol.
MODBUS data tabs format description
Each object accessible by MODBUS communication is described as follows:
Addr
Type
0x0000
char[10]
Where:
• Addr is MODBUS address of hexadecimal register
• Type is data type (see following tab)
• Size is byte size for referred data in decimal
• Name is object identification, generally the same indicated in the "serial connection" paragraph.
• Notes Contains the data description (parameter, measure, etc..) and data representation information.
Data type
Integer
Used integer's codification are described in the following tab:
Type
Description
char
ASCII Characters
byte
Unsigned byte
word
Unsigned word (16 bit)
int
Signed integer (16bit)
long
Signed Long Int (32bit)
ulong
Unsigned Long Int (32bit)
On integer data at 16 and 32 bit listed in the table the format big endian is used, which is the most significant byte first presented in sent/
received data on serial port.
In case the data isn't a pure number the possible measuring units related to the data are the following:
• [rpm] rotation per minute
• [mbar] millibar=10
bar
-3
• [bar*100] represents the pressure in bar with two digit after comma. Ex. In case pressure is 2.34 bar number will be 234
• [°C*10] represents the temperature in Celsius centigrades with one digit after comma. Ex. In case temperature is 125.7°C number will be 1257
• [h] hours
• [min] minutes
• [s] seconds
• [V*100] number represents voltage in Volts with two digits after comma. Ex. In case voltage is 2.15V number will be 215
Reply
0x01
Controller address
0x03
Function
0x00
Byte number
0x0B
Dato (MSB)
0x00
Dato (LSB)
0x01
CRC16 (MSB)
0xF5
CRC16 (LSB)
0xC8
Size
Name
10
MATRICOLA
Range
0..255
0..65535
–32768..32767
–2147483648..2147483647
0..4294967295
Notes
Controller serial number. Refer to menu 10
Length
1 byte
1 byte
2 bytes
2 bytes
4 bytes
4 bytes
0x01
0x03
0x02
0x01
0x02
0x38
0x15
57
W3-0A5 12-I
Publicité
Table des Matières
