Siemens SINAMICS S120 Function Manual page 374

Safety Integrated basic functions
9.5 Safe Brake Control (SBC)
The "Safe Brake Control" function is not selected until at least one safety monitoring function
has been enabled (i.e. p9601 = p9801 ≠ 0).
Two-channel brake control
The brake is controlled from the Control Unit. Two signal paths are available for applying the
brake.
Figure 9-1
The Motor Module carries out a check to ensure that the "Safe Brake Control" function 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
For the response times when the function is selected/deselected via input terminals, see the
table in "Response times".
Examples
Assumption:
Safety monitoring clock cycle time CU (r9780) = 4 ms and
inputs/outputs sampling time (r0799) = 4 ms
t
R_typ
t
R_max
374
Two-channel brake control, booksize
= 4 x r9780 (4 ms) + r0799 (4 ms) = 20 ms
= 8 x r9780 (4 ms) + r0799 (4 ms) = 36 ms
Function Manual, (FH1), 10/2008, 6SL3097-2AB00-0BP5
Drive functions