Selection Of The Speed Actual Measurement; Incremental Encoder; Analogue Tacho Generator; Polarity - ABB DCS 500B Description

Functional Software description
Selection of the
speed actual
measurement
Incremental en-
coder
Analogue Tacho
Generator

Polarity

24
Speed measurement mode is selected by means of parameter
SPEED MEAS MODE (2102).
0 = [ENCODER A+,B dir]
ch A pos edges for speed;
1 = [ENCODER A+-]
ch A: pos. and neg. edges for speed
2 = [ENCODER A+-,B dir]
ch A pos and neg.edges for speed; ch B: direction
3 = [ENCODER A+-,B+-]
ch A and B and pos. and neg. edges for speed and direction
4 = [ANALOG TACHO]
AITAC is used
5 = [EMF SPEED ACT]
speed actual is calculated from the EMF motor;
this is the default setting
If an incremental encoder is used, the number of pulses per revolu-
tion has to be set in the parameter TACHOPULS NR (2101), the
default setting is 2048. It is possible to monitor the received number
of tacho pulses by means of the signal TACHO PULSES (12104),
when SPEED MEAS MODE (2102) is set to value 0...3 or 5.
The analogue tacho generator output voltage must be scaled with
HW circuit so that at maximum drive speed the measured value is
below 10V. This provides a reserve between maximum speed and
limitation of analogue input and gives a possibility to use overspeed
protection. SDCS-CON-2 I/O-board contains the scaling circuit but
with SDCS-IOB-3 I/O-board external circuit must be used (PS5311
tacho generator adaption board). After the A/D-conversion an inter-
nal value +-4095 corresponds to +-10V. To scale this value to the
range of the speed reference 0...20000, there are scaling parame-
ters in AITAC function block:
AITAC CONV MODE (101) = 1 with SDCS-IOB-3 I/O-board
AITAC HIGH VALUE (102)
min. -32768...max. 32767
AITAC LOW VALUE (103)
min. -32768...max. 32767
The polarity of the analogue tacho generator voltage must be posi-
tive with positive speed references and negative with negative
speed references.
Note. If the polarity is false, the drive trips to SPEED MEAS.
FAULT.
ch B: direction
= 3 with SDCS-IOB-1 I/O-board
DCS 500 Software Description