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Safety function
The RESOLUTE FS with BiSS Safety encoder system shall provide a safe position when requested
by the controller.
The following restrictions apply to this claim:
The system installer must perform a verified commissioning test during installation.
The system repairer must perform a verified commissioning test following replacement of system part.
The maximum request rate supported is 32 kHz.
The RESOLUTE FS with BiSS Safety system can support.
BiSS Safety
System
CPW
configuration
type
(bits)
type *
Linear
RSH
36
Linear
RSM
28
Rotary
32
LMM
*
BiSS Safety configuration types are defined in BiSS Safety concept document from iC-Haus.
NOTE: Electrical errors are detected by the evaluation unit comparing CPW and SPW content. See BiSS
Safety for RESOLUTE encoders Data Sheet (Renishaw part no. L-9517-9884) for more information.
When installed correctly, the RESOLUTE FS with BiSS Safety system has mechanical safe position of:
Linear systems: not exceeding 1 mm
Rotary systems: not exceeding 2.5°, refer to
NOTE: Thermal expansion effects of the scale and readhead mounting tolerances are excluded
from the mechanical safe position.
Fault Exclusions:
The following will invalidate the Functional Safety certification of the RESOLUTE FS system, see
Faults caused by cutting and reconnecting the readhead cable or extending the readhead cable.
Incorrect installation of the readhead.
Incorrect installation of the rotary and linear scale.
Dismantling of the RESOLUTE readhead.
Operating the system outside of the limits specified within this installation guide.
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 2
NOTE: For the purposes of the FMEDA calculation the following conditions have been assumed:
Method:
SN29500
Environment: Ground mobile
Temperature: 85 °C
Installation
For the safety function to be valid the instructions detailed in this installation guide must be followed.
RESOLUTE FS with BiSS
Safety encoder system installation guide and safety manual
®
SPW
CPW
SPW
Electrical
(bits)
Resolution
Resolution
Error
28
1 nm
256 nm
512 nm
24
50 nm
800 nm
1.6 μm
32
0.0003"
0.0003"
0.0006"
'Ring technical specifications' on page
for a summary of the FMEDA.
Commissioning test
The following checks MUST be performed when commissioning the RESOLUTE FS with BiSS Safety
system and after any repair of the system:
Error bit check
Maximum
Scale code check
scale
length
21 m
Position count direction
13.4 m
Resolution check
N/A
Evaluation unit monitoring
To achieve full system integrity the evaluation unit must continuously monitor the error condition of the
readhead as specified in the BISS Safety specification and, in the case of fault detection, place the system
into a safe state within the process safety time.
NOTES:
The evaluation unit must have its Functional Safety functions enabled
30.
(as often it is a configuration parameter to turn on Functional Safety functionality).
A persistent fault condition may indicate a hardware failure of the RESOLUTE FS system
or an installation problem.
Maintenance
page
4:
The maintenance check intervals will be defined by the system manufacturer according to their risk
assessment. There are no user serviceable parts within the readhead.
The following maintenance actions are advised:
Check the readhead to bracket screws are correctly tightened.
Check for worn or damaged cable connecting the readhead to the evaluation unit.
Check that the scale has not been damaged or contaminated. If required, clean the system using
approved solvents
(see 'Storage and handling' on page
NOTE: Do not retighten the screws securing the encoder ring as this will change the ring settings.
Repair
Repair of the RESOLUTE FS with BiSS Safety encoder system is only by replacement of parts.
The replacement parts must have the same part number as the original parts. The new encoder system
must be installed and commissioned in accordance with Renishaw's 'Commissioning test', on
In the event of failure the affected parts should be returned to Renishaw for further analysis.
Using damaged parts invalidates the Functional Safety certification.
Proof testing
It is the responsibility of the system manufacturer to define any proof testing of the system. Due to the
diagnostic coverage (DC) and safe failure fraction (SFF) required to achieve SIL2, the encoder can only
support continuous demand use.
Power the encoder system and confirm that the error bit as received by the
BiSS Safety master 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 BiSS Safety
master is active.
Move axis over its full travel and check that no errors are indicated. 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.
Check that the position count direction is as expected.
Move the axis by a known distance and confirm that the position changes
as expected. The tolerance for raising a fault condition is relative to the safe
position determined by the system manufacturer.
5).
Original instructions
page
3.
3
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