Compuprint 3046 Programmer Manual Instrukcja Użytkownika Pobierz pdf (Strona 21)

The link protocol is mainly based on the following three phases:

• Negotiation Phase

This phase is activated always by the host, only when in compatibility mode, and defines:

- whether a bidirectional link protocol can be established.

- the handshaking mode as well as the communications mode to be used.

- the device identification, if supported.

• Communication Phase

This phase is based on well defined handshaking rules which depend upon the selected link mode.

• Termination Phase

This phase is initiated by the host and returns the interface to the compatibility mode.

Description of the signals in monodirectional link:

Signal Name Pin N° Source Description

STROBE 1 HOST Clock signal which controls data transmission with its falling edge.

ACK 10 PRINTER Negative pulsed signal indicating that the printer has received data

and is ready to accept the next set of data. Also sent when the

printer is switched from off-line to on-line and at the end of the

initialization time. The BUSY line is always active.

DATA BIT 1

DATA BIT 2

DATA BIT 3

DATA BIT 4

DATA BIT 5

DATA BIT 6

DATA BIT 7

PRINTER /

HOST

Data 8 is the most significant bit. These are the data lines used by

host to transfer control code or ASCII codes.

DATA BIT 8 9

BUSY 11 PRINTER When high, this signal indicates that the printer cannot accept data

or control codes. This signal goes high during data processing, in

test and program modes, during initialization, when the buffer is

full, and when a paper jam, paper end or paper size error occurs, in

case of a power-on reset, the reception of a STROBE signal, while

the register was not yet read, or when the INIT line is still active.

PE 12 PRINTER When high, this signal indicates that printer is out of paper .

SELECT 13 PRINTER When high, this signal indicates that the printer is on-line.

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Compuprint 3046 Programmer Manual Instrukcja Użytkownika Strona 21