Connecting the Inputs and Outputs of the SM 335
2-9
SM 335 – High-Speed Analog Input/Output Module for the SIMATIC S7-300
6ES7 335-7HG00-8BA1
2.5.1
Correcting the sensor power supply
Purpose
The power supply for the sensors is a 10 V output voltage. This voltage may devi-
ate slightly from 10 V. The deviation results from the tolerances of the components
used on the SM 335. You can therefore read off the exact value of the sensor
power supply for applications requiring very high accuracy.
Sensor voltage ( 10, 11)
The analog value of the sensor voltage (U
G
) is factory-set and stored in the mod-
ule. The SM 335 supplies the analog value of the sensor voltage U
G
in input bytes
ModAdd + 10 and 11 (see Table 3-1 in Subsection 3.1.1).
Correction factor
The correction factor K is computed from the sensor voltage U
G
and the desired
voltage.
K
+
27648 (6C00
H
)
U
G
U
G
lies between 27620 (6BE4
H
) and 27676 (6C1C
H
), producing correction factors
from 0.9989883 to 1.0010127.
Measured value
The corrected analog measured value is computed as follows:
U
Corr
+
K · U
AI
U
Corr
= Corrected analog value
K = Correction factor
U
AI
= Analog value measured at the analog input
