Sartorius la series Operating Instructions Manual page 132

Synchronization
During data communication between
the balance and an on-line device
(computer), messages consisting of
ASCII characters are transmitted via
the interface. For error-free data
communication, the parameters for
baud rate, parity, handshake mode
and character format must be the
same for both units.
You can set these parameters in the
Setup menu so that they match those
of the on-line device. You can also
define parameters in the balance
to make data output dependent on
various conditions. The conditions
that can be configured are described
under each of the application
program descriptions.
If you do not plug a peripheral
device into the balance interface
port, this will not generate an
error message.
132
Handshake
The balance interface (Sartorius
Balance Interface = SBI) has transmit
and receive buffers. You can define
the handshake parameter in the Setup
menu:
– Hardware handshake (CTS/DTR)
– Software handshake (XON, XOFF)
Hardware Handshake
With a 4-wire interface, 1 more
character can be transmitted after
CTS (Clear to Send).
Software Handshake
The software handshake is controlled
via XON and XOFF. When a device
is switched on, XON must be
transmitted to enable any connected
device to communicate.
When the software handshake is
configured in the Setup menu, the
hardware handshake becomes active
after the software handshake.
The data transmission sequence
is as follows:
Balance ––– byte –––> Computer
(transmitting ––– byte –––> (receiving
device) ––– byte –––>
––– byte –––>
<––– XOFF –––
––– byte –––>
––– byte –––>
...
(Pause)
...
<––– XON –––
––– byte –––>
––– byte –––>
––– byte –––>
––– byte –––>
Transmitting Device:
Once XOFF has been received, it
prevents further transmission of
characters. When XON is received,
it re-enables the transmitting device to
send data.
Receiving Device:
XOFF is transmitted after the 26th
character has been stored. To
prevent too many control commands
from being received at one time,
XON is not transmitted until the buffer
is almost empty.
Activating Data Output
You can define the data output
parameter so that output is activated
either when a print command is
received or automatically and
synchronous with the balance display
or at defined intervals (see
application program descriptions and
auto-print setting).
Data Output by Print Command
The print command can be
transmitted by pressing p or by
a software command (Esc P).
device)
Automatic Data Output
In the "auto print" operating mode,
data are output to the interface port
without a print command. You can
choose to have data output
automatically at defined print intervals
with or without the stability parameter.
Whichever parameter you select, the
data will be output as the readouts
appear on the balance display. The
display update frequency depends on
both the model of the balance and
the current operating status.
If you select the auto print setting,
data will be transmitted immediately
the moment you turn on the balance.
In the Setup menu you can
configure whether this automatic
output can be stopped and started by
pressing p.