Siemens SINUMERIK 840C - Manual (Page 946)

12.93 12 Functional Descriptions
12.18.14 Special cases of gearbox interpolation
The following interlocks are effective:
• Inhibition of reconfiguration (axis 1844*)
• Inhibition of link factor switchover (axis 1844*)
• Inhibition of synchronizing position switchover (axis 1844*)
• INTERLOCK LINK OFF (interface signal)
To ensure that the links become active immediately after power on, "LINK ON after POWER
ON" (axis 1844*) must be set for the currently active following axis.
Reference point approach by gantry axes
When a portal machine with gantry axes is switched off, mechanical strains in the portal can
cause misalignment of the axes in relation to one another. A certain sequence must therefore
be followed on restart or when the gantry axes execute their mandatory reference point
approach.
• Absolute measuring system for both gantry axes
When both gantry axes are equipped with an absolute measuring system as the sole
measuring system, there is no need for special referencing since these measuring systems
report their absolute positions to the control after power on. The axes are therefore
"referenced" immediately after power on.
• Incremental measuring system for both gantry axes
During referencing (synchronization) of gantry axes, the axes involved are operated alternately
as either the leading or following axis. In other words, only one of the two gantry axes is
referenced initially (the second operates simultaneously as a coupled axis); the other axis is
referenced afterwards (the first axis then operates simultaneously as a coupled axis). Finally,
any dimensional offset is then eliminated by means of the "On-the-fly synchronization"
function.
Caution:
An undesirable feedback loop develops when both GI groupings are active at the same time.
No check is made for this state. This problem can be best avoided by mutually interlocking the
two gantry groupings by means of the INTERLOCK LINK ON signal.
Prerequisites:
• Automatic reference point approach is active (NC MD 560*.4 = 1)
• Long referencing cams are mounted on portal axis X or X1.
Referencing cam EMERGENCY STOP cam
Axis X or X1
• The following GI groupings have been configured via the input display:
–
GI grouping 1 Leading axis X1; following axis X; link factor 1:1; link type K1; enter
reference point positions as synchronous positions
– GI grouping 2 Leading axis X; following axis X1; link factor 1:1; link type K1; enter
referencing point positions as synchronous positions
© Siemens AG 1992 All Rights Reserved 6FC5197- AA50 12–171
SINUMERIK 840C (IA)