PSI Matrix PP 806 Benutzerhandbuch Seite 129

*) Overlined signal names indicate that the signal is true when the signal level is low.
**) When the interface buffer is full except for the last character, BUSY will not be reset. BUSY will
be reset when buffer space is available again for least 512 characters in the interface buffer. While
the printer is offline (Stop Mode) BUSY remains active until the printer enters the online state again.
IEEE Std 1284 Nibble mode including Device ID are supported.
The maximum throughput for data transfer is 42,000 characters per second.
Transmission Protocol
After Power-ON the PE (Paper Empty) signal is set to low level and the SELECT and the FAULT are
set to high level.
The printer is now ON-LINE and ready to receive data.
Timing
The host sets a print/control character to the 8 data lines.
After a time delay of a minimum of 0.5 µs, the host sends a STROBE pulse of a minimum of 0.5 µs.
When the data byte is accepted into the interface buffer the printer transmits a BUSY signal and an
ACKN pulse.
The ACKN pulse informs the host that the data has been received and that the printer is ready to
receive new data.
If the interface buffer is full except for the last character the BUSY is not reset in order to stop the
data transfer from the host. The BUSY signal is only reset if space is available in the interface buffer
for a minimum of 512 characters.
While the printer is offline, or a serial interface is active BUSY remains high and no ACKN is sent until
the printer enters online state or the serial interface is deselected.
Timing Diagram
Appendix A-7