schmersal PSC1 Series Installation Manual page 62

Installation manual
•
On the usage of compact encoders with a dual-channel internal layout, e.g. SSI +
incremental/SINCOS, the instructions from the manufacturer in relation to the safety-related
properties of diagnostic measures, mechanical connection and measures for the supply of
power are to be followed. The encoder's safety level must correspond as a minimum to the
safety level required for the overall arrangement. Preferably, encoders with proven safety-
related properties are to be used.
In general, the following faults in the external encoder system are detected by the PSC1 module:
•
Short-circuits between the safety-related signal wires
•
Open circuit in the safety-related signal wires
•
Stuck at 0 or 1 on one or all safety-related signal wires
Further specific diagnostics for the detection of faults in the external encoder system are allocated to
each encoder type. The related diagnostic measures are listed in the following for the individual
encoder types together with the limiting parameters
Safety instructions:
•
The diagnostic measures have of course tolerances as a consequence of measurement
inaccuracies. These tolerances are to be taken into account during the safety-related
assessment.
•
The limits for the related diagnostic measures can be configured to some extent or are fixed.
The resulting diagnostic coverages are to be assessed for the related application and included
in the overall safety-related assessment.
PSC1-C-10 Installation manual V2.7
Version: 57E
Page 62 of 174