V2.00
KBR multicomp F144-3PH
61
19837_EDEBD
A0227-1816-1_EN
Data point description for the Modbus protocol
Example 2:
-12.55155 decimal = 0xC148D325 hex
Address
+0
+1
+2
+3
Format
SEEEEEEE
EMMMMMMM
MMMMMMMM MMMMMMMM
Binary
1 1 0 0 0 0 0 1
0 1 0 0 1 0 0 0
1 1 0 1 0 0 1 1
0 0 1 0 0 1 0 1
Hex
C1
48
D3
25
Example 3:
45.354 decimal = 0x42356A7F hex
Address
+0
+1
+2
+3
Format
SEEEEEEE
EMMMMMMM
MMMMMMMM MMMMMMMM
Binary
0 1 0 0 0 0 1 0
0 0 1 1 0 1 0 1
0 1 1 0 1 0 1 0
0 1 1 1 1 1 1 1
Hex
42
35
6A
7F
Exponent:
10000100 bin = 132 dec.
Exp.= 132-127=5
Mantissa: S=0
Sign=positive
01101010110101001111111 bin
Decimal point added to the first position of the mantissa
. 01101010110101001111111
Leading 1 in front of decimal point
1. 01101010110101001111111
Taking exponent into account (=5)
101101. 010110101001111111
to the left of the decimal point:
101101 bin = 25+ 23+ 22+20 = 45 dec.
To the right of the decimal point:
010110101001111111 bin =
2
-2
+ 2
-4
+ 2
-5
+ 2
-7
+ 2
-9
+ 2
-12
+ 2
-13
+ 2
-14
+ 2
-15
+ 2
-16
+ 2
-17
+ 2
-18
= 0.3540001 dec.
Final result: +45.03540001 dec.
3 Interface parameters
Baud rate (Baud)
Parity
Data bits
Stop bits
4800, 9600, 19200,
38400
even, odd, none 8
2 for parity none
1 other
The maximum data length of a Modbus transmission is 256 bytes. This results in a useful
data length of 253 bytes.
The number of data bits and stop bits is defined in the Modbus definition.
Baud rates smaller than 4800 baud are possible by definition, but not implemented at the
moment. The interface parameters can only be configured at the device (not via bus).
