Siemens SINUMERIK 840D sl Function Manual page 64

Safety Functions Integrated in the Drive
4.4 Safe Brake Control (SBC)
Two–channel brake control
The brake is controlled from the Control Unit. The brake can be closed through two
signal paths.
Gating
terminal 1
Fig. 4-1
The Motor Module carries out a check to ensure that the Safe Brake Control func-
tion is working properly and ensures that, if the Control Unit fails or is faulty, the
brake current is interrupted and the brake applied.
The brake diagnosis can only reliably detect a malfunction in either of the switches
(TB+, TB–) when the status changes (when the brake is released or applied).
If the Motor Module or Control Unit detects a fault, the brake current is switched off
and the safe status is reached.
Response time with the Safe Brake Control function
The following values can be specified for the response times when the function is
selected/deselected via input terminals:
S Typical response time
4x safety monitoring clock cycle CU (r9780) + inputs/outputs, sampling time
(p0799)
S Maximum response time that can occur when an error develops
8x safety monitoring clock cycle CU (r9780) + inputs/outputs, sampling time
(p0799)
4-64
SINUMERIK 840D sl/SINAMICS S120 SINUMERIK Safety Integrated (FBSI sl) – 05.2008 Edition
NCU 7x0
DRIVE–
CLiQ
Two–channel brake control, booksize
Control terminal 2
Motor Module
P24
TB+
BR1
Brake diagnostics
TB–
M
BR2
© Siemens AG 2008 All Rights Reserved
05.08
Closed–circuit brake
BR+
Motor
BR–
M