Sartorius LP Models - Data Communication Synchronization; Synchronization and Handshake Methods; Transmitting and Receiving Device Signals

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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.
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)
– 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
(trans- ––– byte –––> (receiving
mitting ––– byte –––> device)
device) ––– 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 in 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 has transmitted all but
14 characters.
If the device addressed does
not understand the control command,
the SBI receiving device activates
DTR (Data Terminal Ready)
after 6 more characters have been
received. The busy signal is
deactivated by XON (14 characters).