
Analog modules
6.6 Analog input module SM 331; AI 8 x 13 Bit; (6ES7331-1KF02-0AB0)
S7-300 Module data
368 Manual, 02/2013, A5E00105505-08
Using PTC resistors
PTCs are suitable for monitoring the temperature of or providing thermal protection for
complex drives and transformer windings. The module has no analog values when PTC
resistances are used. Status information on fixed temperature ranges are displyed instead of
analog values.
● When setting the parameters, select measurement type R "Resistance" and measuring
range "PTC".
● Connect the PTC (see "Terminal diagram for resistance measurement").
● Use PTC resistors that comply with IEC 60034-11-2 (previously, PTC thermistors that
complied with DIN/VDE 0660, Part 302).
● Sensor data for the PTC resistor:
Property Technical
specifications
Comment
Response to rising temperature
< 550 Ω Normal range:
Bit 0 = "0", bit 2 = "0" (in the PII)
550 Ω to 1650 Ω Advance warning range:
Bit 0 = "0", bit 2 = "1" (in the PII)
> 1650 Ω Actuating range:
Bit 0 = "1", bit 2 = "0" (in the PII)
Response to falling temperature
> 750 Ω Actuating range:
Bit 0 = "1", bit 2 = "0" (in the PII)
750 Ω to 540 Ω Advance warning range:
Bit 0 = "0", bit 2 = "1" (in the PII)
Switching points
< 540 Ω Normal range:
Bit 0 = "0", bit 2 = "0" (in the PII)
(RRT-5) °C
(RRT+5) °C
(RRT+15) °C
Measurement
voltage
Voltage at PTC
Max. 550 Ω
Min. 1,330 Ω
Min. 4,000 Ω
Max. 7.5 V
RRT = Rated response temperature
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