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Failure modes effects and diagnostics analysis
All diagnosed failure modes are detected immediately except for a position discrepancy between
the two measurement methods which is detected within 375 μs.
See
'Functional Safety data declaration'
on page
NOTE: For the purposes of the FMEDA calculation the following conditions have been assumed:
Method
SN29500-2005-1
Environment
Ground mobile
Temperature
85 °C for the readhead and 60 °C for the interface
Installation
For the safety function to be valid the instructions detailed in this installation guide must be
followed. The information relating to all scale types and mounting options is listed. The builder/
installer/maintainer/ repairer must apply the instructions for the product being installed as defined
by this installation guide.
The following general conditions must be observed during installation:
•
Observe ESD handling precautions when handling the cable connectors.
•
Cleaning mating surfaces before mounting the rotary or linear scales.
Original instructions
10
for a summary of the FMEDA.
Commissioning test
The following checks MUST be performed following installation and commissioning of the
RESOLUTE Functional Safety Siemens DRIVE-CLiQ encoder system for the first time, and also
following repair of the system (replacement systems parts):
Error bit check
Power the RESOLUTE Functional Safety Siemens DRIVE-CLiQ
encoder system and confirm that the error bit as received by
the Siemens controller is clear. Place business card or similar
between the readhead and the scale to block the light path.
Confirm that the error bit as received by the Siemens controller is
active and stays active once the card is removed.
Scale code check
Clear the error bit (by cycling power to the system).
Move axis over its full travel and check that no errors are latched
with the Siemens controller. This check needs to be performed at
a traverse speed (circumferential speed for rotary) of < 2 m/s to
ensure that the readhead checks every code written on the scale.
Position count direction
Clear the error bit and check that the position count direction is
as expected.
Resolution check
Move the axis by a known distance and confirm that the position
count changes as expected to a tolerance determined by the
manufacturer's risk assessment.
NOTE: Should the working temperature of the readhead need to be measured attach a suitable
sensor directly to the aluminium readhead housing. Do not attach to the label that shows the
product details. Do not drill into the housing as this may compromise the sealing or technical
function. Route the sensor cable away from moving parts and along the same path as the
readhead cable.
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