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Description of the EInt formats
10-6 Description of the EInt formats
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Example:
(See Fielbus option manual for detalied information)
We would like to control the inverter over a bus system using the first two
bytes of the Basic Control Message by setting menu [2661] FB Signal 1 to
49972. Further, we also want to transmit a 16 bit signed reference and pro-
cess value. This is done by setting menu [2662] FB Signal 2 to 42905 and
menu [2663] FB Signal 3 to 42906.
Note It is possible to view the transmitted process value in control panel menu
Operation [710]. The presented value is depending on settings in menus
Process Min [324] and Process Max [325].
The reference value is set in modbus number 42905 (0-4000h) corresponds
to 0-100% of actual reference value.
Modbus parameters can have different formats e.g. a standard unsigned/
signed integer, or EInt. EInt, which is described below. All parameters written
to a register may be rounded to the number of significant digits used in the
internal system.
If a parameter is in Eint format, the 16 bit number should be interpreted like
this:
F EEEE MMMMMMMMMMM
F
EEEE
MMMMMMMMMMM
If the format bit is 0, then can a positive number 0-32767 be represented by bit
0-14.
If the format bit is 1, then is the number interpreted as this:
Value = M * 10^E
Note Parameters with EInt format may return values in both formats (F=0 or F=1).
Example
If you write the value 1004 to a register and this register has 3 significant dig-
its, it will be stored as 1000.
In the floating point format (F=1), one 16-bit word is used to represent large
(or very small numbers) with 3 significant digits.
If data is read or written as a fixed point (i.e. no decimals) number between 0-
32767, the 15-bit fixed point format (F=0) may be used.
F=Format. 1=floating point format, 0=15 bit as 15-bit fixed point format.
The matrix below describes the contents of the 16-bit word for the two differ-
ent EInt formats:
B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
F=1 e3
e2
e1
e0
F=0 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0
Format bit:
0=Unsinged integer mode,
1=Eint mode
2 complement signed
exponent
2 complement signed
mantissa.
m10 m9 m8 m7 m6 m5 m4 m3 m2 m1 m0
Section 10-6
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