Chauvin Arnoux C.A 25 Mode D'emploi page 59

Connection of pin n°1 to pin n°3 makes it possible to change the tripping threshold.
- Pins 1 and 3 not connected.
This operating mode is designed to be used with standard TTL 0-5 V signals or
single polarity signals. The trip threshold is set at + 1.1 V (at 1 kHz). To avoid
problems due to noise which is often present in industrial locations, the threshold
has a hysteresis of 250 mV.
- Pins 1 and 3 connected.
This mode is designed to be used with signals that are symmetrical with the ground
(bi-pole).
This function allows direct measurement from a variable reluctance magnetic
sensor or from the output of an alternator.
The trip threshold is set at 300 mV (at 1 kHz) with a hysteresis of 250 mV, the AC
residual superimposed on the signal to be measured must be less than 250 mV to
avoid interfering with the measurement when the threshold is tripped.
WARNING :
The maximum voltage applied to input n°2 must not exceed ± 20 V.
The electrical ground of the external input socket is electrically connected to
the ground of the RS 232 digital output.
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