Specifications

DATAPROCESS EUROPE S.p.A.

ST3xx ST4xx ST5xx

– PROGRAMMING MANUAL -

Pag.46

Return Codes

The printer can send information about its status to an external device.

Such information can be sent automatically during the reception of data /status of the

buffer), whilst it is processing data or printing (status of the printer) or on request (status

of the sensors).

The transmission of any communication can be inhibited with the command

/$&%.

This

will avoid any undesired interference when there is a connection with a device which does

not receive data from the printer.

Status of the buffer

The control characters ASCII

DC1

(code 11 hex, 17 dec) and

DC3

(code 13 hex, 19 dec),

otherwise known as XON and XOFF, are sent by the printer to advise the external device

on the status of the reception buffer’s internal 64 Kbytes thereby enabling it to control the

data flow even without a physical connection of the RTS line of the printer.

An XOFF character is sent when the RTS line changes level from high to low indicating

that the reception buffer is nearly full (more than 60,000 bytes present).

An XON character is sent when the RTS line changes level from low to high (this occurs

when the printer is switched on and after the initialisation phase) indicating that there is

available space in the reception buffer (less than 50,000 bytes present).

Setting the 14th position of the

/ $&%

command to 1 means that the printer can be con-

figured in such a way that the RTS moves from the print of one label to the next. In this

way the printer will result busy whilst it is printing and will return to “ready” at the end of

the print. This mode ensures that the buffer is never full with labels.

Another way of keeping the printer “busy” is to send the sequence of commands

VT-US-

US-NAK

. The printer will return to ready mode when the reception buffer is completely

empty.

If a composition error is encountered in the data received, the

BEL

character (code ASCII

7) will be sent to inform the external device that some characters may have been lost. This

normally indicates that the transmission line is disturbed.

See the section on Connections with External Devices for more details on the status of the

RTS line and the communication protocols.