KBR multisys 1D3-ESDP Operating Instructions, Technical Parameters page 13

Example 1: -12.5 decimal = 0xC1480000 hex
M: 24-bit mantissa
E: Exponent with an offset of 127
S: Sign for mantissa (S=1 neg.; S=0 pos.)
Address +0
Format SEEEEEEE
Binary 1 1 0 0 0 0 0 1
Hex C1
The byte sequence ist defined as follows:
The byte with the "S sign bit" is transmitted as the first byte via the bus.
The sequence of the float bytes on the bus can be reversed, where required, using the "commands" module (see
table 1).
The following information can be derived from this illustration:
The sign bit is 1 => negative mantissa
The value of the exponent amounts to 10000010 bin or 130 dec.
This yields a value for the exponent of: 130 - 127 = 3
The mantissa contains the following value: 10010000000000000000000
The decimal point can be found at the left end of the mantissa, preceded by a 1. This position does not appear in
the hexadecimal numeric notation. If you add 1 and set the decimal point at the beginning of the mantissa, you
will obtain the following value:
1.10010000000000000000000
Now the mantissa must be adjusted to the exponent. A negative exponent shifts the decimal point to the left, a
positive exponent shifts it to the right. Since the exponent is 3, this appears in our illustration as:
1100.10000000000000000000
The number obtained corresponds to the binary floating-point number.
Binary points to the left of the decimal point yield values > 1. In this example, 1100 bin yields the number 12 dec.
3 2 1
{(1x2 )+ (1x2 )+ (0x2 )+ (0x2
Binary points to the right of the decimal point yield values < 1. In this example, .100....... bin yields the number 0.5
3 -1
dec. {(1x2 )+ (1x2 )+ (0x2
By adding the individual values, 12.5 is obtained. Since the sign bit was set, this is a negative number, that is, -
12.5. The hexadecimal number 0xC1480000 therefore corresponds to -12.5.
Example 2: -12.55155 decimal = 0xC148D325 hex
Address +0
Format SEEEEEEE
Binary 1 1 0 0 0 0 0 1
Hex C1
Version 1.0
+1
EMMMMMMM
0 1 0 0 1 0 0 0
48
Table 5: Example float -12.5
0
)}
-2 -3
)+ (0x2 )}
+1
EMMMMMMM
0 1 0 0 1 0 0 0
48
Table 6: Example float -12.55155
MULTIGATE-Profibus / multisys 1D3-ESDP
+2 +3
MMMMMMMM MMMMMMMM
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
00 00
+2 +3
MMMMMMMM MMMMMMMM
1 1 0 1 0 0 1 1 0 0 1 0 0 1 0 1
D3 25
Page - 7 -