Craden Peripherals DP8 technical manual Writing to the Printer LCD Display, Interfacing, Funct

These fonts can be selected like any other font after loading the driver and selecting the printer as the default printer. They will print and display correctly in WYSIWIG programs like MS Word only if a font size is selected that displays characters at their correct spacing. A font size selection that displays characters at a smaller spacing will print slowly as the printhead repositions to print each character closer than its nominal spacing. MS Word curiously decreases character spacing as larger font sizes are selected. FONTTEST.DOC on the driver disk can be opened in MS Word or Wordpad and printed to demonstrate the resident fonts. Insure that the left margin is set to 0.2" for the fonts and display to read correctly.

3.11.5 Writing to the Printer LCD Display

The driver includes 4 pseudo-fonts that write to the printer LCD display rather than print. The action that selects one of these fonts must be immediately followed by EXACTLY 16 characters to be displayed, without any intervening page positioning commands. All data following the 16 characters will be printed in the font that was selected before the pseudo-font selection. FONTTEST.DOC on the driver disk includes display writes using all 4 pseudo-fonts.

Pseudo-fonts LCD TOP DLY and LCD BOT DLY write to the top and bottom display lines only after all previous data has printed. Pseudo-fonts LCD TOP IMM and LCD BOT IMM write to the top and bottom display lines as soon as they are sent to the printer, even if all previous data has not yet printed. Standard Craden display commands, ESC BEL, ESC FS, ESC DC3 and ESC GS, can still be used by applications able to write control characters to the printer.

3.12Interfacing

The standard interface provides RS-232 communications at 1200, 2400, 4800, 9600, 19200 or 38400 baud and has an 11 Kbyte input buffer. Characters may contain 7 or 8 data bits, even, odd or no parity and 1 stop bit. These parameters are all keypad programmable by 9 3

FUNCT.

3.12.1 Input Buffer Operation

All data received except immediate status, display and reset commands are placed in an 11 Kbyte first-in, first-out buffer. Characters with parity errors are replaced by a "@" and framing errors are replaced by a “~”.

The buffer may be used to receive all commands for printing an entire document. This reduces host attention to the printer but caution must be used to determine correct recovery from document jams and operator intervention during printing.

If a document jams in the printer, printing stops and "DOCUMENT JAM" is displayed. The next status word transmitted will have the document jam bit set. Once notified, the host may write recovery instructions to the display. If the transaction is to be restarted, previously transmitted data can be destroyed by transmitting a DC4 in mode C or a CAN in mode I. The host should request status and check the document jam bit in the status word before re-transmitting data. The operator may also destroy the buffer contents by pressing CLEAR after removing the document and moving the printhead to the left wall. The host must then be notified by the operator that the transaction data may be re-transmitted.

3.12.2 Interface Protocols

Either DTR or XON/XOF protocols may be selected from the keypad. In these modes the DTR signal will go false or a DC3 (Xmit off) will be transmitted if less than 1000 characters of space are available in the buffer when a CR or document movement command is received. Transmission from the host must then pause. DTR will later go true or a DC1 (Xmit on) will be transmitted when space becomes available and host transmission may resume. DTR is equivalent to most systems’ hardware protocol.

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