System modules – Lenze ECSCAxxx User Manual
Page 337
System modules
DFIN_IO_DigitalFrequency (node number 21)
Inputs_DFIN
l
337
EDBCSXA064 EN 3.2
Function sequence
1. The TP is activated in an edge−controlled manner via the digital input X6/DI1 or via a
zero pulse (only if encoder is connected).
2. If a TP has occurred, DFIN_bTPReceived_b is set = TRUE.
3. After the start of the task, DFIN_dnIncLastScan_p indicates the number of
increments [inc] counted since the TP.
4. Following, DFIN_bTPReceived_b = FALSE is set.
)
Note!
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It is necessary that all three outputs (DFIN_nIn_v, DFIN_bTPReceived_b and
DFIN_dnIncLastScan_p) are processed in the task even if just one signal is
required.
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The polarity of the digital input X6/DI1 configured via C0114/1 does not
have an influence on the edge evaluation.
DFIN_nIn_v
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The value DFIN_nIn_v is scaled to increments per millisecond [inc/ms].
– (INT) 16384 corresponds to 15000 rpm. See chapter "Signal types and scaling"
(
¶ 27).
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For every task in which DFIN_nIn_v is used, the operating system creates an
individual integrator that is reset after every start of the task (task−internal process
image).
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For reliable TP generation, DFIN_nIn_v must not be used in the PLC_PRG.
Example: DFIN_nIn_v in a 10 ms task:
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When the 10 ms task starts, the value of the integrator is stored in a local area of the
task and the integrator is reset. The value in the local area gives an average value in
increments per 1 ms.
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If a position value is to be calculated from the average value, the average value has
to be multiplied by (SYSTEM_nTaskInterval / 4) in order to obtain increments per
10 ms.
– At a task of 10 ms, the value of SYSTEM_nTaskInterval is ’40’
(40 × 0.25 ms = 10 ms).
– See also chapter "SYSTEM_FLAGS (system flags)" (
¶ 373).
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The Lenze function blocks already implement this procedure.