137
ifm
Programming Manual
ecomatmobile
CabinetController (CR0301) Runtime System V05
2016-04-21
ifm function elements
ifm function elements for the device CR0301
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PERIOD_RATIO
20441
Unit type = function block (FB)
Unit is contained in the library
ifm_CR0301_Vxxyyzz.LIB
Symbol in CODESYS:
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Description
367
PERIOD_RATIO measures the frequency and the cycle period (cycle time) in [µs] during the indicated
periods at the indicated channel. In addition, the mark-to-period ratio is indicated in [‰]. Maximum
input frequency
→
data sheet.
This FB measures the frequency and the cycle time of the signal at the selected CHANNEL. To
calculate, all positive edges are evaluated and the average value is determined by means of the
number of indicated PERIODS. In addition, the mark-to-period ratio is indicated in [‰].
For example:
In case of a signal ratio of 25 ms high level and 75 ms low level the value RATIO1000 is
provided as 250 ‰.
In case of low frequencies there will be inaccuracies when using FREQUENCY. To avoid this,
PERIOD_RATIO can be used. The cycle time is directly indicated in [µs].
The maximum measuring range is approx. 71 min.
NOTE
For PERIOD_RATIO only the inputs CYL0...CYL3 can be used.
For PDM360smart: CR1071: all inputs.
The output RATIO1000 provides the value 0 for a mark-to-period ratio of 100 % (input signal
permanently at supply voltage).
Frequencies < 0.05 Hz are no longer clearly indicated!
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Parameters of the inputs
17820
Parameter
Data type
Description
INIT
BOOL
FALSE
TRUE (edge):
unit is initialised
FALSE:
during further processing of the program
CHANNEL
BYTE
Number of the fast input channel
0...3 for the inputs IN08...IN11
PERIODS
BYTE
Number of periods to be compared
8406
The FB may provide wrong values before initialisation.
► Do not evaluate the output before the FB has been initialised.
We urgently recommend to program an own instance of this FB for each channel to be evaluated.
Otherwise, wrong values may be provided.
Содержание Ecomat 100 Mobile CR0301
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