Indication And Signalling Concept Of The Heating Current Monitoring - Siemens SIMATIC S5 Manual

Special Functions for Plastic Machines
3.3.5 Indication and Signalling Concept of the
Heating Current Monitoring
The measured and averaged actual voltage value is indicated in message 17. If the actual voltage
value exceeds the positive (negative) tolerance, bit 0 (bit 1) is set in error byte 13.
The measured and averaged actual current values corrected by the amount of the actual voltage for
the ON state are written to message 17 and for the OFF state to message 18. The measured,
unfiltered and uncorrected actual current values for the ON state are written to message 19 and for
the OFF state to message 20. If the corrected actual current value exceeds the positive (negative)
tolerance in the ON state, bit 0 (bit 1) is set in the corresponding error bit. In the OFF state, bit 2 is set
if the positive tolerance is exceeded (see Fig. 3.3.5/1). The error messages are continuously
updated. The reaction to an error message (example: switching off the heating) must be contained
in the S5 program. The time between the occurrence of an error until it is detected by the heating
current monitoring, is up to 19.2 s for hot channel control. With standard temperature control, this
time depends on the sampling time. At a sampling time of 800 ms, it is 6.4 s.
A hardware adapter module for heating current measurement must supply the IP with a
measurement signal, which provides positive sinusoidal half-waves with a maximum peak voltage
of 25.6 V for the actual current values and 10.24 V for the actual power supply voltage value.
Positive sinusoidal half-waves with an amplitude of 25.6 mV or 10.24 V correspond to a d.c. voltage
of 16.3 mV or 6.52 V. If you set a power supply voltage or current setpoint which converts to a value
greater than 16.3 mV or 6.52 V, bit 4 is set in the error bytes and the setpoint is limited to a value
corresponding to 16.3 mV or 6.52 V. If the actual power supply voltage or actual current value
exceeds 16.3 mV or 6.52 V, bit 6 of the error byte is set to 1 and the actual value read in is set to
16.3 mV or 6.52 V.
Fig. 3.3.5/1 Tolerance monitoring
If heating current monitoring is selected, some of the messages and error bytes explained in
Chapter 2 must be replaced by the messages and error bytes shown on the following pages.
IP244
4–88
C79000–B8576–C860–02