Remote Reading - Chauvin Arnoux C.A 25 Mode D'emploi

The value programmed sets the number of seconds separating two successive
printouts, the limits are 10s minimum and 99999 seconds maximum (approx 27
hours).
When the scanning function is ON, the SCAN symbol appears on the display after
is pressed on measurement mode (see paragraph 4.7).
PRINT
If the printout interval exceeds five minutes, the optical emitter of the instrument
is switched off between each measurement ( symbol disappears from
the display), then switched on again 2 seconds before the new measurement.
The auto off function of the C.A 27 is suppressed throughout the operation of the
scanning function. The symbol is lit on the display.
REMOTE INQUIRIES (C.A 27 only)
Foreword: the next five pages are intended for users wishing to develop their own
transmission soltwares. The TACHOGRAPH software, sold as an accessory,
frees you from remote inquiry management.
It is possible to establish a dialogue between the C.A 27 and a computer fitted with
an RS 232 serial type interface. The operation of the serial interface is described
in Appendix II.
The read signals of the C.A 27 must be received on the RxD input.
The read instruction consists of sending a specific code to the instrument. If the
code transmitted does not correspond to a code known by the latter, it ignores the
read instruction. For a read instruction to take effect it has to be sent before or after
an emission sequence of the instrument (the TxD output must be on 1).
The output of the codes starts a maximum of 500 ms after the first character applied
to the RxD input. If a new read instruction arrives during emission, this is ignored.
The read instruction can be used to wake up the instrument which has been
previously set to sleep by an operating time greater than 5 minutes. In this case
sending any character to the RxD input sets off the wake up process and the
measurement is available after a max time of 500 ms plus the length of a cycle of
the measurement signal.
The first read message must arrive at least 250 ms after the first change of condition
of the RxD for it to be taken into account by the microprocessor.
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