10.94 12 Functional Descriptions
12.19.5 DC link buffering and monitoring of generator minimum speed limit
setpoint zero), energy is fed back to the DC link. This drive measures the DC link voltage
cyclically. If the voltage increases above the values set in drive MD 1631 and 1632, the two-
position controller is deactivated, i.e. the instantaneous actual speed value is input as the
speed setpoint. During active generator operation, the ZK2 message "DC link generator
active" (ZWK_GEN_ACTIVE) is output.
The two-position operating characteristics of the generator is specific to the machine and
application.
If the voltage increases above the value set in drive MD 1633, the axis/spindle switches from
generator mode back to speed-controlled operation unless it was operating in position-
controlled mode beforehand. In this case, a drive reset is required (power ON/OFF).
12.20.5.2 Monitoring for generator minimum speed limit
In addition to the generator mode operating characteristics for DC link buffering purposes
described above, the actual speed value of the axis/spindle is also monitored in generator
operation for violation of a minimum speed limit which can be parameterized via a 611D MD
(drive MD 1635). When the speed drops below this minimum limit, the ZK2 message
"Generator speed < drive MD 1635" is output.
Analogous to the detection of violation of the DC link minimum voltage value set in drive MD
1634, this signal can also be defined as an internal error source for "Extended stop and
retract":
See DC link undervoltage monitoring in 611D.
12.20.5.3 Communications/control failure
With the 611D package 2, a communications/control failure is detected when the NC sign of
life fails to appear on the drive bus; an autonomous drive ESR is then executed if this reaction
is programmed.
12.20.5.4 840C/611D detects error/request and specifies "Extendedstop and retract" as autonomous drive function
When the combination 840C SW4 and 611D package 2 is available, it is possible to initiate an
autonomous drive ESR when an ESR source is detected even though the control has not yet
failed. It must be noted in this case that the reaction is defined depending on the source in
question.
12.20.6 Stopping
The stop operation can be parameterized and programmed when SW version 4 is installed:
The following are the stop operation sources:
• Mode group stop (as well as all alarms which initiate mode group stop) and
• EMERGENCY STOP if parameterized by means of NC MD bit.
All sources for retraction can thus also act as sources for the stop operation.
There are two categories of reaction, i.e.
• as an open-loop control function and
• as an autonomous drive function.
© Siemens AG 1992 All Rights Reserved 6FC5197- AA50
12–219
SINUMERIK 840C (IA)