1 + mantisse) value = (-1) – KROHNE CORIMASS MFC 85 Modis EN User Manual
Page 12
Addendum to Operating and Instruction Manual for “Modis” Converters
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Page 12 of 18
2.3 Meaning of the Measuring- and Status Messages
By implementing devices in the PROFIBUS-Master by using the GSD, it is possible to
indicate, which measuring and totalizer messages will be transferred over the PROFIBUS. To
each values a status will be added. First, the 4 value byte (Float Format to IEEE Standard 754
Short Real Number) and then 1 status Byte will be transferred. That means that each
measuring or totalizing value is described with 5 byte and transmitted one after the other
according to the sequence which was projected over the GSD. If 4 function blocks have been
projected, 20 byte will be transmitted.
First an example of the float format:
Byte n
Byte n+1
Byte n+2
Byte n+3
Bi
t7
Bit6
Bi
t7
Bit6
Bit7
Bit7
V
Z
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
2
-
1
2
-
2
2
-
3
2
-
4
2
-
5
2
-
6
2
-
7
2
-
8
2
-
9
2
-
10
2
-
11
2
-
12
2
-
13
2
-
14
2
-
15
2
-
16
2
-
17
2
-
18
2
-
19
2
-
20
2
-
21
2
-
22
2
-
23
Exponent
Mantisse
Mantisse
Mantisse
Example:
40 F0 00 00 (hex) = 0100 0000 1111 0000 0000 0000 0000 0000 (binary)
Formula:
Value = (-1)
VZ
* 2
(Exponent - 127)
* (1 + Mantisse)
Value = (-1)
0
* 2
(129 - 127)
* (1 + 2
-1
+ 2
-2
+ 2
-3
)
Value = 1 * 4 * (1 + 0,5 + 0,25 + 0,125)
Value = 7,5
The meaning of the status (unsigned integer) you will find in following table:
Qualit
y
Quality-
Substatus
Limits
Gr Gr Q
S
Q
S
Q
S
Q
S
Q
u
Q
u
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
0
0
= bad
0
1
= uncertain
1
0
= good (Non Cascade)
1
1
= good (Cascade) - not supported
Status = bad
0 0 0 0 0 0
= non-specific
0 0 0 0 0 1
= configuration error
0 0 0 0 1 0
= not connected
0 0 0 0 1 1
= device failure
0 0 0 1 0 0
= sensor failure
0 0 0 1 0 1
= no communication (last usable value)
0 0 0 1 1 0
= no communication (no usable value)
0 0 0 1 1 1
= out of service
Status = uncertain