Siemens SIMATIC ET 200S - Page 494

Analog Electronic Modules
12-88
ET 200S Distributed I/O System
EWA-4NEB 780602402-12
Use of PTC resistances
PTCs are suitable for temperature monitoring or as a thermal protective device for
complex drives and transformer windings.
• Select ”Resistance 2-wire” and ”PTC” during configuration.
• Connect the PTC in 2-wire technology.
• Use PTC resistances of Type A (PTC thermistor) as per
DIN / VDE 0660, Part 302.
• Sensor data for PTC resistance:
Feature Technical
specifications
Remarks
Switching points Switch on/release
max. 750Ω
Measured resistance < Response value
• SIMATIC S7: Bit 0 = ”0” (in PII)
• SIMATIC S5: Bit 3 = ”0” (in PII)
Powering-down
from 1650 Ω to 4000 Ω
Temperature rise
Measured resistance > Response value
• SIMATIC S7: Bit 0 = ”1” (in PII)
• SIMATIC S5: Bit 3 = ”1” (in PII)
Switch on/release
from 1650 Ω to 750 Ω
Temperature fall
Measured resistance < Response value
• SIMATIC S7: Bit 0 = ”0” (in PII)
• SIMATIC S5: Bit 3 = ”0” (in PII)
(TNF--5) _C
(TNF+5) _C
(TNF+15) _C
Measuring circuit
voltage
Voltage at PTC
max. 550Ω
Min. 1330 Ω
Min. 4000 Ω
Max. 7.5 V
TNF = rated response temperature