Siemens SIPROTEC 7SJ64 - Measured Value (Float)

Data type definitions
50
SIPROTEC PROFIBUS-DP - Communication profile
C53000-L1840-B001-03
3.5 Measured value (float)
Number of
byte-values
4
Range of values +/- 1,7 * 10
38
Figure 3-5 Data type: Measured value (float)
Sign bit (S) The sign bit is set for negative measured values.
Measured value The value of the measured value results as follows:
Note:
Measured values in float format are only available for Transrapid protection devices
(7ST622).
All other SIPROTEC devices use measured values in signed integer format for trans-
mission (ref. to chap. 3.4).
Byte 3 (MSB) Byte 2 Byte 1 Byte 0 (LSB)
S
Exponent (8 Bits)
Message head ... ... Message end
Fixed-point part (23 Bits)
0 < exponent < 255: value = (-1)
<sign>
∗ 2
<exponent> - 127
∗ 1.<fixed-point part>
exponent = 0: value = 0
exponent = 255,
fixed-point part
≠ 0:
invalid