KEB COMBIVERT F5-A, Applications Manual, Page: 298 / 552

Page 7.12 - 6 COMBIVERT F5-A, -E, -H © KEB, 2012-10
Posi- and synchronous operating
7.12.2.1 Approach to reference point / modes
There are 3 different Modes of position reference:
PS.14: Mode of position reference
Bit Meaning Value Explanation
0/1
Mode of positi-
on reference
0: off No approach to reference point
1: no auto-
start Approach to reference point is started via digital input. The input is
defined with
PS.19.
2: autostart
The approach to reference point is carried out automatically during
the first "start positioning” command after "power on", even if the po
-
sitioning mode has not been activated yet (input with function "Posi-
tioning /synchronous activation" not set). If the approach to reference
point is interrupted (e.g., by switching off the control release), all
other "start positioning" commands also start an approach to refe-
rence point. Has the reference point search been completed once,
no approach to reference point can be initiated with "start positioning"
anymore. If, additionally, an input is occupied with the function "ap-
proach to reference point", this input is also active.
3: last positi-
on (at power-
on-reset)
The software limit switches are immediately active (if programmed in
Pn.66). The switching condition „approach to reference point com-
pleted“ is met. The value for the actual position (ru.54) is generated
as follows:
●
Encoder without absolute position information (e.g., incremen-
tal encoder) : After "power on" the actual position is = the last ac-
quired actual position before "power off". To ensure that the position
is correct, the encoder may not turn anymore after power off.
●
Encoder with single-turn absolute position information (e.g.,
resolver) : After "power on", the position is read out by the encoder
within one revolution, the count of whole revolutions is taken from the
last actual position before "power off". To ensure that the position is
correct, the encoder may turn maximally ½ revolution after power off.
●
Encoder With multi turn absolute position information :
The current actual position is read from the encoder after "power on".
In mode 1 and 2, the approach to reference point is started on the rising edge of input "start approach to refe-
rence point" (mode 1) and "start positioning" (mode 2), respectively.
The approach to reference point starts with the speed adjusted in PS.21 "reference speed". The direction of
rotation which is used first for the reference point search (the preferred direction f rotation) is
set by the sign
of PS.21 . A positive sign means the drive first looks for the reference point switch in the clockwise direction of
rotation.
The acceleration / deceleration ramps during the approach to reference point are not defined via the OP para
-
meters but via PS.20 "reference acc./dec. time".
Attention: the ramp time and the approach to reference point speed must be chosen so that the drive can stop
and reverse as long as the reference point switch is active. Otherwise, faulty referencing can occur (e.g., stop
on the wrong side of the reference point).
To achieve the most precise referencing, an "approach to reference point free drive-speed" can be programmed
in PS.22. for free driving of the reference switch. If this parameter is set to "0:off", the free drive-speed is taken
as ¼ of the approach to reference point speed (PS.21) .
The actual position is overwritten with the value of PS.17 "reference point" at the reference point.