Parker iqan-mc3, Руководство пользователя

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Voltage inputs
7 I/O functionality
Instruction book, IQAN-MC3
Tolerances on voltage inputs in safety functions
The unit has automatic monitoring of the internal analog-to-digital converter, that is
capable of detecting gain errors of 3% or higher. An internal error causing a smaller
signal drift than 3% is not detected by the check.
.
Connecting switches to the voltage inputs
Connection of switches to voltage inputs will in most cases be restricted by the
restriction of signal range on voltage inputs used in safety functions.
A voltage input may be connected to a switch, but it shall use +VREF, the switch may
not be connected to +BAT.
N
OTICE
The VIN are designed for permanent connection to +BAT, but not for +BAT transients.
Therefore VIN connection to +BAT should be avoided.
MC3-SMR-008:A Tolerances on VIN
When voltage inputs are used in safety functions, the application shall be designed
so that it can tolerate a gain error of 3% on the voltage inputs and still be in a safe
state.
EXAMPLE
For a safety related hold-to-run function controlled by a proportional lever, the
function is in a safe state when the lever is in its neutral position, corresponding to an
output signal of 2500mV. To ensure that the function does not get activated when
the lever is in its neutral, a deadband is needed.
With a lever that has a tolerance of +-200 mV in the neutral position (typically 10%
in each direction), the deadband in the application must be 13% or more.
Deadband.
IN
OUT
10
100
100
-100
-100 -10