NORD Drivesystems BU0510 - Manual (Page 21)

3 Description of function
BU 0510 GB-3911 Subject to technical alterations 21
NOTE
The direction of rotation of the incremental encoder must comply with the direction of rotation
of the motor. With a positive output frequency (clockwise rotation) the actual position value
must increase. If the direction of rotation is not correct, this can be adjusted with a negative
value in P607 "Speed Ratio".
With the aid of a value which can be parameterised in parameter P609 [-01] "Offset Position" the zero point
can be set to a different position to that which is determined by the reference point. The offset is applied after
conversion of the encoder rotations to motor rotations. After changes to the speed ratio/reduction ratio
P607 [-01] and P608 [-01] the offset position value must be entered again.
3.2.1.1 Reference point run via digital inputs or BUS I/O In bits
The Reference point run is started via one of the digital inputs or one of the Bus IO In bits. For this a digital
input must be programmed for the appropriate function (P420-P425 or P470 "Function Digital Input", setting
22). For the Bus IO In Bits the corresponding Bit / Array (P480 "Bus IO In Bits", setting 22) must be
parameterised. The direction of the reference point search is specified via the signals "Enable Left/Right". The
current setpoint frequency determines the speed of the reference point run. Via one of the digital inputs the
reference point is also read in. For this a digital input must be programmed for the appropriate function
(P420-P425 or P470 "Function Digital Input", setting 23). For the Bus IO In Bits the corresponding Bit / Array
(P480 "Bus IO In Bits", setting 23) must be parameterised.
In order to also realise the function "Reference Point Run" via a serial interface or via the Bus IO In bits, one of
the "Bus Setpoint Values" (P546, P547 and P548) must be set to the setting "Bus IO In Bits 0...7" and under
P480 "Function Bus I/O IN Bits" the function setting 22 must be assigned to the corresponding bit.
Sequence of the reference point run: With the reference point run enabled, the drive unit moves in the direction
of its setpoint value (Enable Right/Left, +/- Setpoint). On reaching the reference point switch, the signal at the
digital input or Bus IO In Bit "Reference Point" reverses the direction of travel. Therefore the drive unit moves
away from the reference switch again.
If the drive unit is already at the switch at the start of the reference point run, the reference point run is
immediately started with the inverse direction of rotation.
After leaving the switch, the actual position is set to the value which is set in parameter P609 "Offset Position".
If the value in parameter P609 "Offset Position" is not "0" then the drive immediately moves to its new zero
position and remains at this position until the "Reference Point Run" signal is removed.
In the setpoint mode P610 "Position Increment Array" = 1 (relative positioning) the setpoint position is
simultaneously set to 0. With appropriate parameterisation of one of the parameters "Digital Output Function"
(P434, P441, P450, P455, setting 20 - reference point), the frequency inverter reports the end of the reference
point run with corresponding adoption of the reference point. The feedback for the end of the reference point
run can also be reported via the Bus IO OUT bits (P481, "Bus IO Out Bits", setting 20).
If an incremental encoder without the function "Save Position" is used (See P604 "Encoder Type") the actual
position in parameter P601 "Current Position" is set to "0" when the frequency inverter is switched on. For
parameterisation with the function "Save Position" the last saved value is taken as the actual position.
The relay or output message "Reference Point" shows that a valid reference point is available. The relay or
outputs are switched off when a reference point run is started and are switched on again after completion of
the reference point run.
If the option "Save Position" (P604 "Encoder Type") is not selected (factory setting) the relay or the output are
switched off when the inverter is switched on.
If the option "Save Position" is selected the relay or the output are switched on immediately after the inverter is
switched on. Control via one of the Bus IO Bits is correspondingly identical.