Siemens SIMATIC S5-90U System Manual page 451

S5-90U/S5-95U
Function
Analog input module 464-8MF21 is suited for the connection of resistance thermometers (e.g.
PT 100) and is provided with an interruptible internal linearization.
The resistance of the PT 100 is measured in a four-wire circuit. A constant current is supplied to
the resistance thermometer via terminals 7 and 8 as well as via terminals 9 and 10. The voltage at
the resistance thermometer is measured via terminals 3/4 and 5/6. In this way, highly accurate
measuring results are obtained.
1
2
Figure 15-18. Wiring Method for PT 100 (6ES5 464-8MF21)
Start-Up of Module
Set the intended operating mode using the switch on the front panel of analog input module
464-8MF21. This switch is located on the right side at the top of the front panel of the module.
Power supply Set the switch to the available power supply frequency. This selects the inte-
frequency: gration time of the A/D converters for optimal interference voltage suppression.
Power frequency 50 Hz:
Power frequency 60 Hz:
Operation: Set the number of channels you wish to assign on the input module.
Broken wire: Once the broken wire signal has been activated, a break on one of the lines to
the sensor or of the sensor itself causes the red LED above the function
selection switch to light up. At the same time, the broken wire error bit F (bit 1,
byte 1) for the faulty channel is set.
EWA 4NEB 812 6115-02b
M0 M1 I 0 I 1
+ + C + C +
3 5 7 9
4 6 8
10
Integration time 20 ms
Integration time 16.66 ms
Module Spectrum
Terminal assignments:
(3/4): Measuring circuit M0
(5/6): Measuring circuits M1
(7/8): Constant current circuit I
(9/10): Constant current circuit I
0
C
1
C
15-85