EvitaXL

LUST protocol
LUST:
List-controlled universal interface driver program compatible
with the RS 232 interface in Evita from software version 7.n
upwards.
The LUST protocol comprises four different transmission
telegrams:
— Identification telegram
— Status telegram
— Data telegram
— Alarm telegram
The first three telegrams are only sent in reply to a request
from the external unit. The alarm telegram is sent automatically
when an alarm occurs or disappears.
Telegram control
The following ASCII* characters are used to request the individual
telegrams:
"ACK" Request for an identification telegram
"NAK" Request for a status telegram
"ENQ" Request for a data telegram
Output of all telegrams can be controlled via certain characters:
"DC1" (x-on) Enables telegram output
"DC3" (x-off) Halts output at any time
Following an enable ("DC1"), the interrupted telegram is output
again without being adjusted to the actual status.
The effect of "DC3" is cancelled by a request for a telegram;
the telegram interrupted by "DC1" is lost and the requested
telegram is sent.
Output of an alarm telegram can also be controlled:
"DC2" Enables output of the alarm telegrams
"DC4" Halts the output of alarm telegrams
Ongoing transmissions are not interrupted by "DC4". This is
only possible with "DC3" (x-off).
A telegram request ("ACK", "ENQ" or "NAK") does not re-enable
the output of alarm telegrams.
Following a "DC2", the last event is transmitted by the alarms
in each case. If alarm events have not occurred, an alarm telegram
with all active alarms is requested with each "DC2".
Unknown control characters are ignored.
* For a list of special ASCII characters used, see page 237.
Technical Data
LUST protocol
Instructions for Use EvitaXL 201