NORD Drivesystems BU0710 - Manual (Page 17)

3 Functional characteristics
BU 0710 GB 17
Incremental shaft
encoder on the
motor --- 24…31
24: 500 marks absolute 1 revol. mode 2
.....
31: 5000 marks absolute 1 revol. mode 2
yes
The example shown above is based on a multiplication and demultiplication ratio of "1". The maximum position
value or the overflow point respectively is calculated as follows:
N
max
: max. value of motor shaft revolution
±n
max
= ± 0.5 * Ü
b
/ U
n
Ü
b
: multiplication (P607)
U
n
: demultiplication (P608)
Example: The absolute value shaft encoder is mounted on the output face of a gearbox. The multiplication factor of the
gearbox is i = 26.34. The following values are parameterised: n
max
= ± 13.17 Umdrehungen
3.3 Setpoint setting
Essentially four methods of setpoint setting are available. Setpoints can be fed to the system via digital inputs
as absolute or as relative position values, or they can be transmitted over a bus. The way the actual position is
ascertained is irrelevant for setpoint setting. Absolute, relative and bus setpoints can be defined whether an
absolute encoder or an incremental encoder is used to determine the actual position.
3.3.1 Position array – Absolute setpoint position via digital inputs
In the "position array" position setpoint mode, up to 63 positions per parameter set can be selected via the
digital inputs 1 through 6. The position numbers result from the binary value of the inputs. For each position
number one position setpoint can be parameterised. The position setpoint is either entered via the control
panel (of the control box or the parameter box) or the "NordCon" parameterisation software (by reading the
current position and saving it as the setpoint in the inverter's memory) or made permanent by "teach-in"
programming which implies that the operator will "demonstrate" to the system how to make the driven
assembly adopt the various positions.
3.3.2 Position increment array – Relative setpoint position via digital inputs
The "position increment array 2" position setpoint mode is especially suitable for rotary shafts. A value can be
assigned to each of the 6 digital inputs which will be added to the setpoint position when the signal changes
from 0 to 1 . As both positive and negative values can be used, control also allows for returning to the original
position. The addition is made with any positive signal edge whether the inverter is enabled or not. By applying
several pulses to one input, the multiple of the parameterised increment can be preset. The pulse width as
well as the width of the pulse intervals must be 10 ms minimum.
3.3.3 16-bit bus mode
The setpoint can be transmitted via any of the various field bus activation circuits available. The position is fed
to the system in terms of revolutions. The resolution is 1/1000 rev. For setpoints to be transmitted via the serial
interface, the applicable option must be enabled in the P509 "Interface" parameter included in the "Additional
Functions" menu group. Parameter P546 (Bus - setpoint 1) is accessed to define whether 16 or 32 bits are to
be used for setpoint transmission. For detailed information regarding bus setpoints see the relevant
supplementary operating instructions.
3.3.4 32-bit bus mode
Same as 3.3.3, the word length being 32 bits however. In this mode the setpoint exactly corresponds to the
value represented in P602 (one motor revolution = 1000 in P602 and 1000
10
if transmitted as a bus setpoint).
3.3.5 Position array – Bus transmission of absolute setpoint position
Basically as 3.3.1, except that the position numbers are defined using bits 0...6 of the serial interface. In this
mode, the setting "Posicon control terminals" will have to be selected for one of the bus setpoints (P546, P547,
and P548).