Danfoss iC7 Series Operating Manual page 16

Operating Guide | iC7 Series Functional Safety
Table 3: Instances of STO Feedback for Systems with Modular Control
State
Bootloader and startup
Internal failure
Internal fatal failure
1) Energized: STO_FB+ ⇨ STO_FB- circuit closed = current flow = logical "0" with low side driver configuration. De-energized: STO_FB+ ⇨ STO_FB- circuit open = no current flow =
logical "1" with low side driver configuration.
A External safety device
Figure 4: STO Feedback Example with an External Safety Device for System Modules
It can also be used as a digital output for providing a status signal. In this case, the load could be a digital input of a PLC.
STO and STO feedback are activated when 1 or both safe input channels are de-energized.
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(continued)
(1)
Feedback state
De-energized
De-energized
De-energized
Additional information
The bootloader does not communicate and does not
know the state of the STO output on the power units.
At startup, the communication is not yet established
and the safe input card does not know the state of the
safe output on the power units.
Indicates a severe issue, for example in the STO cir-
cuitry. It cannot be assumed that the Safety IO knows
that all STO outputs are de-energized.
Triggered when a fatal internal issue has occurred, for
example, a CPU or RAM fault. The operation cannot be
guaranteed, and it cannot be assumed that the safe
outputs can be de-energized.
B Supply
iC7 Functional Safety
AQ477043679710en-000102 / 172K2965A