Distributed I/O System ET 200S

Analog electronics modules
4.2 Analog value representation
Measured Values in the Event of Wire Break Dependent on Enabled Diagnostics
For the measuring range tables
• 1 V to 5 V, 4 mA to 20 mA
• Temperature sensor Pt xxx Standard and Climatic, Ni xx Standard and Climatic, Cu 10
Standard and Climatic
• Thermocouple type E, N, J, K, L, S, R, B, C, T
the following supplements and rules apply:
Table 4-1 Measured Values in the Event of Wire Break Dependent on Enabled Diagnostics
Format Parameter assignment
S7
• Enable "wire break" diagnosis (at 1 V
to 5 V, 4 mA to 20 mA, RTD) 1
• Enable "wire break test" diagnostics
(with TC)
• "Wire break" diagnostics disabled (at
1 to 5 V, 4 to 20 mA, RTD) 1
• "Overflow/underflow" diagnostics
enabled
• "Wire break" diagnostics disabled (at
1 to 5 V, 4 to 20 mA, RTD) 1
• "Overflow/underflow" diagnostics
disabled
• "Wire break test" diagnostics disabled
(with TC)
1 Measured value limits for wire-break and undershoot detection:
1 to 5 V: at 0.296 V
4 mA to 20 mA: at 1.185 mA
Measured values
Description
Decimal Hexadecimal
32767 7FFFH • Diagnostics message "wire break"
32767 7FFFH • Diagnostics message "wire break"
-32767 8000H • Measured value after leaving the
undershoot range
• "Value under low limit" diagnostic
message
-32767 8000H • Measured value after leaving the
undershoot range
--- --- • Open input: Undefined measured
value
4.2.2 Analog Value Representation for Measuring Ranges with SIMATIC S7
Analog value representation
With the same nominal range, the digitized analog value is the same for input and output
values. Analog values are represented in two's complement.
The following table shows the analog value representation of the analog electronics
modules.
Table 4-2 Analog Value Representation (SIMATIC S7 Format)
Resolution Analog Value
Bit number 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Significance of the bits S 214 213 212 211 210 29 28 27 26 25 24 23 22 21 20 ET 200S
4-2 Manual, 12/2005, A5E00514527-03