Lenze DDS Global Drive PLC Developer Studio - Manual (Page 15)

Function block library LenzeElectricalShaft.lib
Special functions
2.1.1 Digital frequency ramp generator (L_DFRFG)
2−5
L
LenzeElectricalShaft.lib EN 1.2
2.1.1.6 Set offset
The offset is adjusted with dnOffset (1
º 1 incr.).
The offset refers to the digital frequency input and is normalised (scaled) to 1 revolution (= 65536
increments).
Select the constant FIXED0% (selection number 1000) using bSetTPReceived_b = TRUE starts the
ramp generator. The lead of the master from the moment of starting, or the resulting distance/phase
difference, is taken up during acceleration.
·
Setting: positive offset values
– Causes a time−shift of the TP
– This means that less time is necessary to obtain synchronism with the master. (For instance,
with dnOffset = 0 this cannot be achieved).
Note!
With large offset values and low input speeds the drive could change direction. To prevent this, you
can use bySpeedDirection to fix the direction of rotation:
·
bySpeedDirection: 1 = cw/ccw, 2 = cw, 3 = ccw
2.1.1.7 Start of the ramp generator
Use byFunction to parameterize the start of the ramp generator.
byFunction = 0:
The ramp generator is started immediately on the first call.
byFunction = 1:
The ramp generator is now started through bSetTPReceived_b .
2.1.1.8 Use of L_DFRFG with the 9300 Servo PLC
Note!
See also Manual 9300 Servo PLC",
Description of the system blocks DF_IN_DigitalFrequency and MCTRL_MotorControl.
Nature of the task:
·
A 9300 Servo PLC is to be synchronized to the speed setpoint at the digital frequency input.
·
The digital frequency input provides a constant speed of 867 rpm through DFIN_nIn_v:
DFIN_nIn_v + 947 +
15000
rpm @ 16384
867
rpm
·
The start of synchronization is made by the TouchProbe input of the SB
DF_IN_DigitalFrequency (X5/E5).
·
Through the FB L_DFSET a phase−angle difference is controlled down to zero with the help of
the phase−angle controllers in the SB MCTRL_MotorControl.
·
The maximum speed for the ramp generator must not exceed 3000 rpm.
·
Both right (cw) and left (ccw) rotation of the motor are permitted.
·
The acceleration (run−up) time should be 10 seconds.