Glossary
© 2010 Wieland Electric GmbH | BA000256 | 12/2012 (Rev. I)
45
7 Glossary
System Functions
Input circuit function
The input circuit function logically links input signals for further processing. In order to
detect faults (e.g. in the external circuitry of safety inputs) the inputs are tested periodically in
relation to function (external input dynamization).
Input circuit function single-channel via NC contact
One input is monitored (e.g. the NC contact of an emergency stop button). A
valid input signal is only generated if ON state (H-level) is present at the input
and it was previously in OFF state (L-level).
Input circuit function single-channel with testable sensors
Testable sensors (e.g. type 2 non-contact safety devices) are
monitored. A valid input signal is only generated if ON state (H-level)
is present at the input and it was previously in OFF state (L-level).
Input circuit function with dual-channel equivalent activation
Two equivalent inputs (e.g. the opening contacts of an
emergency stop button or actuated N/O contact / N/C contact
of two safety-door position switches)
are monitored.
A valid input signal is only generated if ON state (H-level) is
present at both inputs and both were previously in OFF state
(L-level). The function can be used with/without cross-circuit
monitoring and with/without synchronous time monitoring.
Input circuit function with dual-channel non-equivalent activation
Two non-equivalent inputs are monitored. A valid input signal
is only generated if ON state (H/L-level) is present at both
inputs and both were previously in OFF state (L/H-level). The
function can be used with/without cross-circuit monitoring
and with/without synchronous time monitoring.
Two-hand function with activation by one NO contact per hand (EN 574, IIIA)
Two equivalent inputs are monitored (e.g. the NO contacts of the two two-
hand buttons). A valid input signal is only generated if ON state (H-level) is
present at both inputs within 0.5 s (synchronous change, both two-hand
buttons actuated) and both were previously in OFF state (L-level). For jog
mode the ON signal can be temporarily restricted to 5 s if required.
Two-hand function with activation by NO/NC combination for
each hand (EN 574, IIIC)
Two pairs of non-equivalent inputs are monitored (the NO/NC contact pairs of
the two two-hand buttons). A valid input signal is only generated if ON state
(H/L-level) is present at both inputs within 0.5 s (synchronous change, both
two-hand buttons actuated) and both were previously in OFF state (L/H-level).
Dual-channel equivalent activation by semiconductor
Two equivalent inputs are monitored (e.g. the signals from a light barrier). A
valid input signal is only generated if ON state (H-level) is present at both
inputs and both were previously in OFF state (L-level).
Safety inputs
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