turck BL20 Series - 12.1.9 Limit values of count mode

357
2020/09
12.1.9 Limit values of count mode
Specific conditions must be fulfilled in order to ensure that internal and external events are pro-
cessed correctly. The following sections describe the limit values for both types of events.
Minimum number of count pulses between internal events
A certain minimum number of count pulses must be ensured between the parameters when setting
Upper count limit, Reference value and Lower limit value.
This ensures that internal operations are carried out before a new event occurs.
Illustration of the minimum number of count pulses between two events in relation to the counter
frequency:
f = Counter frequency in Hz
Fig. 254: Limit values of count mode
Counter frequency Minimum number of count pulses at
different count frequencies
200 kHz 2000 pulses
100 kHz 1000 pulses
50 kHz 500 pulses
10 kHz 100 pulses
1 kHz 10 pulses
0
(upper count limt - reference value) > f * 0,01 s
(upper count limit - load value) > f * 0,01 s
(reference value - load value) > f * 0,01 s
(load value - lower count limit) > f * 0,01 s
reference
value
load value
upper
count limit
lower
count limit