Siemens SINUMERIK 840C - Manual (Page 871)

12 Functional Descriptions 12.93
12.12.1 Execution of the function "Path dimension from the PLC"
Manual traverse commands (traverse keys) are ignored while the path dimension is being
traversed from the PLC.
If G68 is passed down the command channel, the path dimension on a rotary axis is traversed
along the shortest path (< 180°). The function G68 precludes the functions G90/G91. The
function G68 is active only for axes to which the partial function ”modulo programming” has
been assigned.
12.12.2 Termination of the function ” Path dimension from the PLC ”
The path dimension function is terminated when an acknowledgement has been sent to the
PLC (command channel).
• Positive acknowledgement (normal mode)
The function ”Path dimension from the PLC” is acknowledged positively when the
remaining path still to be traversed has reached the ”Exact stop window coarse” (MD
204). The acknowledgement frees the channel again, i.e. program mode can be continued
or restarted. If the channel is in the RESET state and if the path dimension is started, then
an NC start cannot be executed. The channel returns to the RESET state once the path
dimension is terminated. The path dimension cannot be started when a part program is
running (see negative acknowledgement).
• Negative acknowledgement (error condition)
If an error occurs during path dimension processing, then the function is acknowledged
through specification of an error number (DB 41, DWm + 1).
12.12.3 Interruption
The path dimension function is interrupted when the following conditions are fulfilled:
• Reset by key
• RESET by a PLC user program
• Change in operating mode
• EMERGENCY STOP
• Warm start
• Cancellation of controller enable command
• Follow-up mode
• Parking axis
• Traverse beyond the software or hardware limit switch or the working area limitation.
Note
All alarms which disable NC processing or mode group readiness to operate likewise terminate
the path dimension function. There are no additional alarms specific to the path dimension
function. If the function is aborted, then it is merely acknowledged negatively through
specification of an error number in DB41, DWm + 1. The function is also terminated when the
operating mode is changed without initiation of a reset.
When the following conditions are fulfilled, the active path dimension can be stopped; traversal
can however be continued until the desired position is reached:
• Feed override 0 %
• Axis-specific feed inhibit (PLC interface signal)
NC stop and feed stop do not have any effect on an active path dimension function.
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SINUMERIK 840C (IA)