Specifications

DATAPROCESS EUROPE S.p.A.
ST3xx ST4xx ST5xx
– PROGRAMMING MANUAL -
Pag.12
only 2 metres with the Leptons parallel cable. The parallel cable is not a standard cable. A
faster communication speed is achieved with the parallel connection and this is strongly
recommended when the windows drivers are used together with the ST4xx series.
10.3 Network
Used to connect a number of printers to the same PC. The network uses a NSA-047/N
converter for each printer as well as one for the PC. The maximum number of printers
and/or applicators in a network is 14.
11 Serial communication protocols
The reception channel buffer has an interrupt limit of
65535
bytes (FIFO) which are read
in sequence by the Command Interpreter.
On switching on the
RTS
signal remains inactive (negative level) until the initialisation
phase is complete. It will then become active (positive level) indicating that the printer is
ready to receive data.
The RTS signal is logic high level if the printer is switched on and its reception buffer is
not full. If the receiving buffer is full and contains more than 60000 characters, the
RTS
switches to logic low level. The RTS becomes high again when the number of characters
in the buffer is less than 50,000.
The margin of 5535 characters is used to avoid the loss of data when the transmission
does not immediately stop on the change of the RTS status from high to low.
An
XOFF
character (ASCII
DC3
, code 13 hex, 19 dec) is sent to the printer when the
RTS
is low whereas an
XON
character (ASCII
DC1
, code 11 hex, 17 dec) is sent when
the
RTS
is high. This standard (protocol
XON/XOFF
) permits simple connections with
three wires, using only
RxD
,
TxD
and
GND
leaving
CTS
and
RTS
open. This is for data
that goes from the printer to the PC. The XON/XOFF protocol has not been used for data
that goes from the PC to the printer to avoid that, during the transmission of a graphic im-
age, a sequence of bits can be interpreted as an XON or XOFF. Consequently the protocol
for the data that goes from the PC to the printer is only controlled by the CTS. For this
reason cables with rx, tx, cts, rts, gnd should always be used to make the printers function
properly.
The printer stores data received from an external device in its buffer even if it is OFF
LINE and will then process it when it is put ON LINE. Even in this case the RTS signal
will go low if the printer fills the buffer with more than 60000 characters.
The command interpreter will send a BELL character (ASCII code 7) to the external de-
vice if it detects an error in the data received thereby warning the device that the data
could be lost. This normally happens when there is a disturbance on the transmission line
or if the communication parameters are wrong.
The transmission channel is also cushioned but with a buffer of 4096 characters. If the
CTS signal is at the logic high level, the printer will send the character on the line. If in-
stead the CTS is at the logic low level, the character to be sent on the line is put in the
buffer. If for any reason during the printing of a batch of 9999 labels, the equipment con-
nected to the line keeps the CTS low, the printer will continue to print and put into the
buffer all information relating to P09999, P09999, P09997 etc. This until the buffer is full