11.03
3 Safety-Related Functions
3.11 Encoder mounting arrangements
© Siemens AG 2003 All Rights Reserved
SINUMERIK 840D/SIMODRIVE 611 digital SINUMERIK Safety Integrated (FBSI) - Edition 11.03
3-171
Interface signal
"Reference point reached" = "1" Axis state "axis referenced"
"Reference point reached" = "
0
" Axis state "
axis not referenced
"
For 840D DB31-48, DBX60.4 / DBX60.5
The function SBH/SG can only be used when this state has been reached (after
run-up has been completed) (refer to Fig. 3-36, "Axis states during
referencing").
For
incremental encoders
, the position actual value is lost when the NC is
powered-down. When the NC is powered-up, a reference point approach must
be carried out. If it is done correctly, then the axis is referenced and goes into
the "axis referenced" state (refer to Fig. 3-36 "Axis states during referencing").
Unlike incremental encoders,
absolute encoders
do not require a reference
point approach after the NC is powered-up. These encoders save the absolute
position, e.g. using a mechanical gear, both when powered-up and powered-
down. The absolute position is transmitted implicitly via a serial interface when
the NC is powered-up. After the position data has been transmitted and the
offset value has been taken into account, the axis is also in the "axis
referenced" state (refer to Fig. 3-35, "Axis states during referencing").
The "axis referenced" state is displayed using the axis-specific interface signal
"referenced point reached" as follows:
Interface signal
"Reference point reached" = "
1
" Axis state "
axis referenced
"
"Reference point reached" = "0" Axis state "axis not referenced"
For 840D DB31-48, DBX60.4 / DBX60.5
References:
/IAD/, SINUMERIK 840D Installation & Start-Up Guide
To reach the axis state "axis safely referenced", the axis state "axis referenced"
must have been reached and either
•
the user confirms the current position per user agreement
or
•
a pre-history (saved and set user agreement and a saved stop position
when the system is powered-down) must exist. The position of the pre-
history must match the current position within a tolerance window. This is
checked both in the drive and in the NC.
The axis state "axis safely referenced" is displayed via the SGA "axis safely
referenced". Only when this state is reached can a safe position evaluation be
made for the functions SE and SN (refer to Fig. 3-36, "axis states during
referencing").
The user agreement function (protected using a key-operated switch) allows
the user to confirm that the current position at the machine corresponds to the
position displayed in the NC.
User agreement is confirmed using a soft key. Before this can be done, the axis
state "axis referenced" must have been reached. If the axis is in this state and
the user has confirmed the position by means of the agreement function, then
the "axis safely referenced" state is also reached.
"Axis referenced"
state
"Axis safely
referenced" state
User agreement
