Parker iqan-mc3, User Manual

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38
Proportional outputs
7 I/O functionality
Instruction book, IQAN-MC3
There are faults that are detected on startup, and that will prevent the module from
starting the application. These are all faults where an output is connected to +BAT on
startup.
To detect these faults, it is important that all connectors are plugged-in before the
module is started. See section Start-up, on page 42.
For details on failure modes, see Appendix B, on page 51.
Reset of faults
The reset behaviour of the COUT is configured in the application file, see IQANdesign
user manual.
Use of COUT in safety functions
COUT safe state
The COUT is assumed to be in a safe state when the output is off; in this state only the
leakage current is delivered (see Appendix A, on page 46).
Minimum current
This is to ensure that there is no movement when the output is off.
Error detection limits
The COUT has a separate, built in monitoring that detects deviations from the
commanded output current. To avoid spurious trips, it is designed to tolerate some
deviation, refer to ’under/over current threshold’, see Appendix A, on page 46.
An undetected error that falls within these limits can lead to an unintentional change of
speed of the output, and must be safe in the application for which the IQAN-MC3 is
used.
During normal operation, when there is no fault; the accuracy is significantly better
than the error detection limits.
Undetected wiring faults
There are COUT wiring faults that are not detectable by the IQAN-MC3, see Appendix
B, on page 51.
All types of wiring faults must be considered to ensure that the failures are safe in the
application.
You should also note that there are wiring errors that can only be detected on start-up of
the unit.
MC3-SMR-012:A Minimum current when using COUT as power driver
When the load connected to the COUT is capable of initiating a hazardous
movement, it shall be designed so that it is only activated if the current is > 50 mA.
MC3-SMR-013:A COUT error detection limits
The application shall be designed so that changes of output current up to the
undercurrent and overcurrent threshold are safe.
MC3-SMR-014:A COUT undetected wiring faults
The application shall be designed so that undetected wiring errors on COUT are
safe.