Step Motor Command - ABB AC 31 Technical Manual

3. Step motor command

ABB Control - AC 31
1SBC 260400 R1001-b 06.99
Program Optimization
The 40 and 50 series central units allow the command of a step motor.
Usage of the NPULSE function block automatically validates the step motor command.
In this case the O62.00 output is used.
VALID
RESET
FREQUENCY
NB_PULSES
The VAL input of the NPULSE function validates the pulse generation.
The pulse train always starts with a high level signal (+ 24 V d.c. in the case of a transistor
output) with a 50% cyclic ratio (see Figure 6-5).
50%
T
Figure 6-5 : 50 % cyclic ratio
The frequency of the pulse generator lies between 10 Hz and 2.6 kHz.
The frequency is determined in the following manner:
Frequency (Hz) = 1 / (256-FREQUENCY) x 384 )
FREQUENCY=0 Frequency = 10.1 Hz
FREQUENCY=1 Frequency = 10.212 Hz
FREQUENCY=2 Frequency = 10.253 Hz
...
FREQUENCY=10 Frequency = 10.586 Hz
...
FREQUENCY=100 Frequency = 16.693 Hz
...
FREQUENCY=254 Frequency = 1.302 kHz
FREQUENCY=255 Frequency = 2.604 kHz
The number of pulses is between 0 and 32767.
The number of pulses already generated may be visualized. The error of the value currently
being executed is ± 1.
NPULSE
VAL
RESET
READY
FREQ RDY
VALUE
NB VAL_P
Page 6-9