Siemens simatic s7-1500 User Manual page 26

Parameters/address space
4.1 Measuring types and ranges
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. Select "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/R/RTD/TC HF
module with PTC resistors.
Figure 4-1
The diagram below shows the temperature profile and the corresponding switching points.
Figure 4-2
26
Address space for the AI 8xU/R/RTD/TC HF module with PTC resistors
Temperature profile and the corresponding switching points
Analog Input Module AI 8xU/R/RTD/TC HF (6ES7531-7PF00-0AB0)
Manual, 09/2016, A5E36647959-AB