11.03 8 Application examples
8.2 Two-channel brake control with SI (SPL)
© Siemens AG 2003 All Rights Reserved
SINUMERIK 840D/SIMODRIVE 611 digital SINUMERIK Safety Integrated (FBSI) - Edition 11.03
8-445
The "position controller active" signal (DB3x.DBX 61.5) represents a further
condition to release the brake. The "speed controller active" signal (DB3x.DBX
61.6) should be used in conjunction with Safety Integrated, because when
Stop C is active the position controller is inactive but the speed controller
remains active, which means that the drive would work in opposition to the
brake.
Note
For this type of control, there is a risk that single-channel actuation of the
brake or the holding brake may not operate correctly in the event of a
PLC fault and that, in the worst case, the axis may fall.
8.2 Two-channel brake control with SI (SPL)
In order to increase the safety-relevant quality of the brake control system (for
the holding brake or operating brake), it is necessary to use a two-channel
control system. An NCK output switches the P voltage (24 V) to release the
brake and a PLC output (S7 relay module) switches the M voltage (P/M
control). A checkback contact on the PLC side verifies that the two switching
elements are operating correctly.
Controlling the NCK output (relevant signals – suggestion):
•
"STOP A/B active”
• $VA_DPE[machine axis name] (power enable status – axis-specific)
available in software version 5.x and higher
• Alternatively or in addition, system variable $AC_ALARM_STAT
(information about the queued alarm response) (already in
software V4.4.x)
• Application-specific SPL signals such as "EMERGENCY STOP not active”,
"control system not powered-up”, etc.
Connecting these signals to $A_OUTSE (NCK output)
Controlling the PLC output (relevant signals – suggestion):
Equivalent programming measures should be implemented on the PLC side (up
to the $A_OUTSEP variable), i.e. further shutdown conditions can be integrated
to control the output.
• "STOP A/B active”
• SGA "pulses safely cancelled”, axis DB.DBX 108.2
• Status signal "pulses enabled”, axis DB.DBX 93.7
• Status signal "speed controller active”, axis DB.DBX 61.6
• Application-specific SPL signals such as "EMERGENCY STOP not active”,
"control system not powered-up”, etc.
Description
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$VA
DPE
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