Siemens simatic ET 200MP - Using PTC Resistors

Parameters/address space
4.1 Measuring types and ranges
Analog Input Module AI 8xU/I/R/RTD BA (6ES7531-7QF00-0AB0)
Manual, 03/2019, A5E44792324-AA
19
The tables of the input ranges, overflow, underrange, etc. are available in the appendix
Representation of analog values (Page 52).
Note
Wire break in voltage measuring ranges
"Wire break" diagnosis can be configured for the "Voltage" measurement type with the
"Measuring range 1 to 5
V". No "wire break" diagnostics is available for the other measuring
ranges.
If there is a wire break for these measuring ranges, the channel supplies a random value as
an input value. This random value can also lie within the valid value range.
Using PTC resistors
PTC resistors are suitable for temperature monitoring of electrical devices, such as motors,
drives, and transformers.
Use Type A PTC resistors (PTC thermistor) in accordance with DIN/VDE 0660, part 302. In
doing so, follow these steps:
1. Choose "Resistor (2-wire terminal)" and "PTC" in STEP 7.
2. Connect the PTC using 2-wire connection technology.
If you enable the "Underflow" diagnostics in STEP 7, it will be signaled for resistance values
<18 Ω. In this case, this diagnostic signifies "Short-circuit in the wiring".
The following figure shows the address space assignment for the AI 8xU/I/R/RTD BA module
with PTC resistors.
Figure 4-1 Address space for the AI 8xU/I/R/RTD BA module with PTC resistors