Analog Value Representation For Measuring Ranges With Simatic S7 - Siemens SIMATIC ET 200iSP Operating Instructions Manual

Analog electronic modules
14.8 Representation of analog values
Format of the analog values S7
Table 14-8 Measured values in the event of a wire break depending on diagnostic enables (format S7)
Module Parameter assignment
4 AI I
• "Wire break" diagnostics ena‐
bled
• "Wire break" diagnostics disa‐
bled
1
• Enable "Overflow/Underflow"
diagnostics
• "Wire break" diagnostics disa‐
bled
1
• "Overflow/underflow" diagnos‐
tics disabled
4 AI RTD • "Wire break" diagnostics ena‐
bled
4 AI TC
• "Wire break" diagnostics disa‐
bled
1 Measuring range limits for the detection of wire breaks in the measuring range 4 to 20 mA: at < 3.6 mA
14.8.2

Analog value representation for measuring ranges with SIMATIC S7

Analog value representation
The digitized analog value is the same for input and output values with the same nominal range.
Analog values are represented in two's complement.
The following table shows the analog value representation of the analog electronic modules.
Table 14-9
Bit number
Pulse value of the bits
Sign
The sign of the analog value is always in bit number 15:
• "0" → +
• "1" → -
376
32767
-32768
-
32767
-
Analog value representation (SIMATIC S7)
Resolution
15 14
Sig 2
14
n
Measured values
decimal hexadecimal
7FFF
H
8000
H
-
7FFF
H
-
Analog value
13 12 11 10 9
2 2 2 2 2
13 12 11 10
Operating Instructions, 11/2022, A5E00247483-AK
Explanation
• Diagnostic message "Wire break"
• Measured value after exiting the
underrange
• Diagnostic message " Low limit ex‐
ceeded"
• Measured value after exiting the
underrange
• Diagnostic message "Wire break"
• Open input: Undefined measured
value
8 7 6 5 4
2 2 2 2 2
9 8 7 6 5 4
3 2 1 0
2 2 2 2
3 2 1 0
ET 200iSP