Printronix S828, Programmer'S Manual

Page: 368 / 424

Programmer Manual PTX ‐ S828
Appendix B ‐ Interfaces 366 260071 ‐ 001A
PrtClk (nAck)
Compatibility Mode: Pulsed low by the printer to acknowledge the transfer of a data from the host.
Negotiation Phase: Set low to acknowledge 1284 support, then set high to indicate that the Xflag
(Select) and data available flags may be read.
Reverse Data Transfer Used in both Nibble and Byte Modes to qualify data being sent to the host.
Phase:
PrtBusy (Busy)
Compatibility Mode: Driven high to indicate that the printer is not ready to receive data.
Negotiation Phase: Reflects the present state of the printer’s forward channel.
Reverse Data Transfer
Nibble Mode:
Data bits 3 then 7, then forward channel busy status
Phase:
Byte Mode:
Forward channel busy status.
Reverse Idle phase: Forward channel busy status.
AckDataReq (PError)
Compatibility Mode: Driven high to indicate that the printer has encountered an error in the paper path.
The printer shall set nFault low whenever it sets PError high.
Negotiation Phase: Set high to indicate 1284 support, then follows nDataAvail (nFault).
Reverse Data Transfer
Nibble Mode:
Data bits then 6.
Phase:
Byte Mode:
same as nDataAvail (nFault)
Reverse Idle phase: Set high until host requests data transfer, then follows nDataAvail (nFault).
Xflag (Select)
Compatibility Mode: Set high to indicate that the printer in on-line.
Negotiation Phase: The Xflag refers to extendibility flag. Used by the printer to reply to the requested
extendibility byte sent by the host during the negotiation phase. The signal level is
low for Nibble Mode, high for Byte Mode.
Reverse Data Transfer
Nibble Mode:
Data bits 1 then 5.
Phase:
Byte Mode:
Same as negotiation phase.
Reverse Idle phase: Same as negotiation phase.
Xflag (Select)
Compatibility Mode: Set low by host to put the printer into auto-line feed mode.
Negotiation Phase: Set low in conjunction with 1284 Active (NSelectIn) being set high to request a
1284 mode.
Then set high after printer sets PtrClk (nAck) low.
Xflag (Select)
Reverse Data Transfer
Nibble Mode:
Set low to indicate that host can receive printer-to-host data then set
Phase: high to acknowledge receipts of that nibble.
Byte Mode:
Same as Nibble Mode to request and acknowledge bytes. Following a
reverse channel transfer the interface transitions to idle phase when
HostBusy (nAutoFd) is set low and printer‘s no data available.
Reverse Idle phase: Set high in response to PtrClk (nAck) low pulse to re-enter reverse data transfer
phase.
Is set high with 1284 Active (nSelectIn) being set low, the 1284 idle phase is being
aborted and the interface returns to Compatibility Mode.
Peripheral Logic High (+ 5V)
Set high to indicate that all other signals sourced by the printer are in valid state. Set low to indicate the
printer is off.