Digital Output - Chauvin Arnoux C.A 43 FILEDMETER Mode D'emploi

The C.A 43 has a digital output. This bi-directional interface allows the instrument to
communicate with external peripherals.
To connect the instrument, use the optic fibre and the opto-electric adaptor. This transforms
the optic signal into a usable electric signal. The optic fibre connects to the COM output of the
instrument (see lug for correct position). The 25 pin opto-electric adaptor connects to the serial
port of the computer or the printer. The mode changer and 25/9 pin reducer could be useful
to you as applicable.
This serial output is not perfectly bi-directional as the micro-controllers used do not allow a full
duplex link.
The convention adopted for this link only takes into account, on the Rx input, the first transition
0 -> 1 which is taken as an interruption for the output. At this point, the instrument sets to
receiver mode to decode the message.
Thus, during a transmission, any character sent to input Rx will block it at the end of the current
output.
If an ON character is then sent, the output will start again at the point where it was interrupted,
in the same function. But if a code corresponding to another message is sent to the instrument,
the output will start again in the new function requested. If an OFF code is sent, the instrument
definitively exits the interrupted output mode.
At the end of each transmission, an ASCII 4 code is emitted to indicate the end of the frame.
This allows the peripheral which is connected to know that it can interrupt the transmission.
If the request to interrupt comes before the end of emission character, this command will not
be taken into account until the end of the frame.
A frame consists of a set of information which can not be separated. When you print a current
measurement, this frame is equivalent to a line. For a measurement in MIN/MAX recording
mode, it is three lines.
The transmission levels are set as follows :
- Level 1 = light present
- Level 2 = no light present
The transmission rate is 1200 bauds
The link-up format is set:
- 1 START bit/8 data bits/1 STOP bit/no parity
Transmission code: All the transmission characters are in ASCII code, except for the
transmission of rapid measurements which are transmitted in a specific format.

DIGITAL OUTPUT

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