Hach sc1000 Profibus DP/V1 Manuel D'utilisation De Base page 15

sc1000 SETUP
OUTPUT SETUP
mA OUTPUT INT/ECXT
Select OUTPUT card 1, 2, 3 or 4.
Default value: No source
Selects a probe or creates a formula which delivers
SELECT SOURCE
the process value that is processed by the current
output card.
Default value: No Parameter
SET PARAMETER
Selects a parameter of the selected source.
Default value: INPUT VALUE
DATA VIEW
Sets the displayed and logged measured value.
SET FUNCTION Default value: LINEAR CONTROL
Default value: 10 mA
Sets the substitute value for the output current in
SET TRANSFER
case the selected source reports an internal error,
is disconnected from the system or its output mode
is set to 'Transfer value'.
IEEE 745 floating point definition
Profibus uses 32-bit single precision IEEE floating point definition. The
definition has twenty three bits for the mantissa and eight bits for the
exponent. There is one bit for the sign of the mantissa. Refer to
Figure 8.
Figure 8 Floationg point definition
1 Sign bit
2 Expoent
3 Mantissa
Word wise swapping
Table 2 shows swapped and normal byte sequences. In word wise
swapping, the third and fourth bytes are interchanged in order with the
first and second bytes. This results in a byte order of 3 4 1 2.
Table 2 Byte order inside Profibus telegram
sc controller swapped
Byte T1 value 0 x 91
Byte T2 value 0 x B9
Byte T3 value 0 x 3F
Byte T4 value 0 x 67
4 Exponent
5 Mantissa
sc controller normal
Byte T1 value 0 x 3F
Byte T2 value 0 x 67
Byte T3 value 0 x 91
Byte T4 value 0 x B9
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