Lenze Global Drive PLC Developer Studio - Manual (Page 77)

Drive PLC
System blocks − Extension Board 3
7.3 DFIN_IO_DigitalFrequency (node number 21)
7−9
L
DrivePLC DE 6.0
Functional sequence
1. The TP is signal−controlled via the digital input X3/I1 of the basic unit or a zero pulse (only if an
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!
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.
DFIN_nIn_v
·
The value DFIN_nIn_v is scaled in increments per millisecond.
(INT) 16384 corresponds to 15000 rpm. See chapter 1.2.7, "Signal types and normalisations".
( ^ 1−8)
·
For every task in which DFIN_nIn_v is used, the operating system creates an individual counter
that is reset after every start of the task (task−internal process image).
·
For reliable TP generation, DFIN_nIn_v must not be used in the PLC_PRG.
Example (DFIN_nIn_v in a 10 ms task):
·
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.
·
If a position value is to be derived from this value, then it must be multiplied by
SYSTEM_nTaskInterval / 4 to get the result in increments per 10 ms, as in the example.
Example: In a 1 ms task SYSTEM_nTaskInterval is 4 (4 x 250 ms = 1 ms)
·
For Lenze FBs, this process has already been implemented in the FBs.