ABB A43 User Manual page 186

Communication with M-Bus
The data, together with information regarding coding, length and the type of data
Data records
is transmitted in data records. The maximum total length of the data records is 240
bytes.
The following table shows the structure of the data record (transmitted left to
right):
Data Record Header
Data Information Block (DIB)
DIF
1 byte
Each Data record consists of a data record header (DRH) and the actual data.
The DRH in turn consists of the data information block (DIB) to describe the
length, type and coding of the data, and the value information block (VIB) to
give the value of the unit and the multiplier.
Data information
The DIB contains at least one byte (Data Information Field, DIF), and is in some
cases expanded with, a maximum of 10, DIFE's (Data Information Field Exten-
block (DIB)
sion).
The following table shows the structure of the Data Information Field (DIF):
Bit 7
Extension bit
1. Least significant bit.
The following list explains the content of the DIF:
A43/A44
User Manual
DIFE
0-10 bytes
Bit 6
1
LSB of storage No.
• The Extension Bit is set when the next byte is a DIFE.
• The LSB of storage No. is normally set to 0 to indicate actual value.
(1=stored value).
• The Function Field is set to 00 for instantaneous values, 01 for maximum
values and 10 for minimum values.
• The Data Field shows the format of the data. The following table shows
the coding of the data field:
Code
0000
0001
0010
0100
0111
1010
1011
1100
186
Value Information Block (VIB)
VIF VIFE
1 byte 0-10 bytes
Bit 5 Bit 4
Function Field Data Field
Meaning
No Data
8 Bit Integer
16 Bit Integer
32 Bit Integer
64 Bit Integer
4 digit BCD
6 digit BCD
8 digit BCD
Data
0-n bytes
Bit 3 Bit 2 Bit 1 Bit 0
Length
0
1
2
4
8
2
3
4
2CMC48001M0201
Revision: C