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Voltage inputs
7 I/O functionality
Instruction book, IQAN-MC3
NOTICE
The negative terminal of the sensor must not be connected to the chassis.
Maximum load for VREF position: see Appendix A, on page 46.
Selection of sensors
The voltage inputs are designed for potentiometer type sensors and for 5V hall effect
sensors.
Sensors with ’padding’ at the min and max limits of the signal range will ensure that
the most common (i.e. short circuits, broken wires) wiring errors are detected.
For potentiometer type sensors with a 0.5-4.5 V range, we recommend that the
potentiometer resistance is 1000 Ohm.
Using voltage inputs in safety functions
The following addional information applies when the inputs are used in safety
functions, where an incorrect input signal can lead to an immediate increase of the risk.
Limits on signal range
By limiting the normal operating range of voltage input signals, several faults can be
detected. For this check to be effective, the signal range must not be too wide.
Calibration Limits:
• Min voltage: >=200 mV
• Max voltage <=4800 mV
VREF usage
It is recommended that the connected sensors shall use one of the VREF’s from the
IQAN-MC3, especially when voltage inputs are used in safety functions. If an external
5 V reference is used, it is up to the application to ensure that the reference voltage is
correct.
Using a common VREF.
Pairs of inputs may use a common VREF.
MC3-SMR-007:A Limits on VIN signal range
When voltage input signals are used in safety functions, the active signal range shall
be limited within 200-4800 mV; and the limits shall be implemented in IQANdesign.
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