Network Support Encyclopedia 9/novell-nsepro-1992-vol09.iso/download/print.txt

Text File | 1992-03-16 | 15KB | 300 lines

                                 SNA NOTE

SNA NOTE 3-129   3287 Host Printer Emulation

APPLIES TO:  Novell 3270 Printer Support

SUPERSEDES: 3-13, 3-22, 3-47, 3-55,and 3-102

DATE: November 6, 1990

The printer support provided with Novell's multi session 3270 products
allows a PC attached printer to serve as a host addressable 3287 printer.
The printer data stream may be sent to a printer directly attached to a
workstation customized for a printer session, or redirected to another
printer on the LAN.

The following information is a consolidation of NOTES regarding printer
support.  It is not intended to be a substitute for the instructions in the
Gateway and Workstation manuals.

HOST CUSTOMIZATION
Bind Considerations
Configure the host in the same way as for a real 3287 printer.  The device
must be LU Type 1 or LU Type 3.  Certain bytes in the bind must be set as
noted below or the Gateway will reject the bind.  The bind is a SNA message
from the host to a terminal or PC that establishes the protocols that will
be used to run the session.  (The IBM Information Display System 3174
Control Unit Functional Description (GA23-0218) has further information
about the bind.)

     Byte 6; Bit 1 must be set to 0 (counting from 0 as the left most bit).
This byte refers to common protocols.  The Novell Gateway does NOT support:
             - "Function management header exchange", which is a part of
               the data stream in SNA architecture.
             - Extended data stream capabilities with LU Type 1.

     Byte 9; must be non zero for LU Type 1.  This byte refers to primary
to secondary pacing count, which defines the number of RUs (request units)
that may be received by the 3174 before a pacing response must be returned
to indicate readiness for another block of RUs.

     Because the printer is slower than the displays, care must be
exercised in this setting pacing so that waiting RUs and/or chains are not
stacked in the 3174 link buffers.  During the transmission of multiple
chains, the 3174 uses printer buffers as an extension of the link buffer
pool and pacing is based on total buffer capacity.  If the printer buffer
becomes full and outbound data is received faster than the data can be
printed, a sense code of X'0801' will be received.

     The setting of pacing count is closely associated with the setting of
MRU (Maximum RU size).  Pacing Count (PC) is commonly set to 1, but the
following formula described can be used to calculate it more exactly for
better performance.

     Refer to LU Type 1 pacing and "RU Lengths"in the SNA chapter of the
IBM 3174 Control Unit Functional Description for further information.





                    BUFF-336
             MRU<   ---------   -13
                       PC

MRU is the smallest multiple of 256, greater than or equal to the maximum
RU size specified in byte 11 of the bind.
PC is the pacing count specified in Byte 9 in the bind.
BUFF is the device buffer size.  The gateway supports a buffer size of
4096.  For a channel attached 3174 the RU size is further constrained to a
maximum of 1536 bytes.  A sense code of X'1002' will occur if the bind RU
size is exceeded.

Changing the Default Page Length for the Printer
Because the host normally overrides operator settings for page length on
the 3287, the best way to change the default page length for the printer is
to add an FCB image to the system image library.  The FCB image is then
pointed to by the FCB parameter of the SYSOUT DD JCL statement for the
system program that is handling the printing, such as VPS or TSO.  Building
a FCB image and adding it to the image library is explained in detail in
the OS/VS2 system Programming Library Data Management Manual.  This task is
usually managed by the systems programmer.

Escape Codes
For each printer to be used, enter the escape sequence for both 6 and 8
Lines Per Inch. It is important to enter these escape sequences in the
correct place;
     LPT 1-5 for parallel printers
     COM 1-4 for serial printers

The LPT and COM selections available will depend upon whether the
Workstation Control Program is customized for LOCAL or LAN printing.  While
holding down the ALT key, enter the appropriate escape sequences from your
printer's manual.  To avoid interjecting unwanted spaces into print output
do not use the space bar to move through the field.  Use the delete key to
clear the field if necessary.

The escape sequence fields are nine characters in length, thereby providing
the ability to add multiple escape sequences in addition to those for 6 and
8 LPI.  For example, the escape codes for compressed print could be
included.  As the control program checks the escape sequences every time it
is about to print; it will then always print the 3287 datastream in
compressed mode until the escape sequence is changed.

NOVELL SOFTWARE PRINTER CONTROL PANEL
After the workstation control program is loaded, the Novell software
Printer Control Panel can be accessed by the appropriate key combination
(see the NetWare Workstation User's Guide).  This screen is an image of the
left half of the front panel of a 3287 printer (the one IBM refers to as
Stage 2), plus the selector switches from the right side of the panel.  All
printer interactions should be done via this panel.  To make any
adjustments ,such as changing paper, press the "hold print" button on the
Novell Software Panel, not the "offline" switch on the printer itself.

When the software Printer Panel appears, it will show "LPT 1" in the upper
left hand corner.   Use the page down key to scroll through the possible
Lpt or Com selections until the correct printer assignment appears.  With a
101 keyboard, use alt/page down (on numeric key pad) to change to the
proper printer.


Changing Line Length
The default line (maximum presentation position) on both a real 3287 and
Novell's printer emulation is 132 characters.  This can be increased to up
to 255 characters for LU Type 1 (for Workstations prior to Version 2.0, PTF
216 is required).   The line length can be specified in the LU Type 1 data
stream using the Set Horizontal Format sequence.  This process is described
in detail in the IBM "3287 Printer Models 1 and 2 Component Description"
document.

The line length can also be set via the software Printer Control Panel;
however, the maximum length which can be set there is 199 characters.  To
change the line length follow this procedure:
     1. Press "Hold Print" (2)
     2. Press "Set Alter" (4)
     3. Use the letters "C", "D", and "E" to enter in the desired line
     length.  "C" corresponds to hundreds, "D" to tens, and "E" to units.
     If "C" is pressed the Status Indicator box will blink.  This means the
     hundreds column is set.  If the box is not blinking, then the length
     is less than 100.
     4. Press "Set Param" (B) to save the new number.
     5. Press "Enable Print" (3)
     6. Press Host "On" (1)

Changing Lines Per Page
The selector switches on the software Printer Control Panel can be used for
setting the number of lines per page.  Page length can be set between 1 and
99 lines; 6 lines per inch is standard for an 8 1/2 x 11 inch page.
Because the host can override operator settings, setting the lines per page
or the line length basically is just a means of setting the defaults (e.g.,
66 lines per page, 132 characters per line).  Refer to the IBM 3287 Printer
Manual mentioned above for a further description of controls, SCS format,
etc.

Printer Status Codes
Error conditions from the physical printer are indicated in the "STATUS
INDICATOR" box on the software Printer Control Panel.  The Workstation
software is made aware of these conditions by examining the "status byte"
that can be read from an I/O port.  Parallel printers can indicate two
distinct error conditions to the PC: temporary error condition (out of
paper or printer offline) or permanent error condition (printer powered
off).

Serial printers can indicate the same two conditions; however, this is
dependant upon the make of the printer and the exact wiring of the serial
cable.  In order for the workstation to receive and distinguish both
conditions, the printer must support the indication of these through the
use of two distinct RS232C pins and the cable must be wired so that these
signals are delivered to the standard pins on the PC end.  (See SERIAL
PRINTER CABLING below for details.)

When the physical printer runs out of paper or is switched offline, the
Workstation Control Program starts a one minute timer.  At that time, the
status indicator in the software Printer Control Panel changes to "01."  If
the physical printer returns to a ready condition before the timer expires,
no sense code is sent to the host and further host data is held off (by not
acknowledging the data already received).  If the printer is still not
ready when the timer expires, then an x'0802' INTERVENTION REQUIRED is sent
to the host, and the indicator in software Printer Control Panel changes to
"31".

When the "hold print" button is pressed on the software Printer Control
Panel, a ten minute timer is started.  If the one minute timer mentioned
above is already running, it is cancelled and replaced with the new ten
minute timer.  However, the indicator on the Printer Control Panel
continues to read "01".  Here again, further host data is held off.  If the
ten minute timer expires without the "enable print" button being pressed on
the Printer Control Panel, an x'0802' sense code is sent to the host, and
the indicator in the software Printer Control Panel changes to "08".  if
the "enable print" button is successfully pressed before the timer expires,
then no sense code is sent to the host.  However, if the physical printer
is still not ready, then an attempt to press the "enable print" button will
be ignored and, when the ten minute timer expires, the x"0802" sense code
will be sent.  Thus, the "hold print" button effectively extends the time
available to load paper or otherwise make the physical printer ready
(online), from one minute to ten minutes.

It is possible to change the duration of these timers by using the
following debug routine: For LU Type 3:
     C> pczap iprtlu3.exe

     Command => s 0 '26C747350100'
     Match at offset X' 285E'.

     Command => s 0 '26C747350a00'
     Match at offset X' 286A'.

     Command => v 285E '26C747350100'
     Data verifies.

     Command => r '26C74735nn00'.
     (nn is the replacement for the one minute timer.  May be a number
between 01-FF minutes.)      Replace completed.

     Command => v '286A '26C747350A00'
     Data verifies.

     Command => r '26C74735nn00'
     (nn is the replacement for the ten minute timer.  May be a number
between 01-FF minutes.)      Replace completed.

     Command => exit

For LU Type 1:
     C> pczap iprtlu1.exe

     Command => s 0 '26c747350100'
     Match at offset X' 2A4A'.

     Command => s 0 '26C747350A00'
     Match at offset X' 2A56'.

     Command => v 2A4A '26C747350100'
     Data verifies.

     Command => r '26C74735nn00'
     (nn is the replacement for the one minute timer.  May be a number
between 00-FF minute.      Data replaced.

     Command => v 2A56 '26C747350A00'
     Data verifies.

     Command => r '26C74735nn00'
     (nn is the replacement for the ten minute timer.  May be a number
between 00-FF minutes.      Replace completed.
     Command => exit

If EITHER the physical printer is powered off or the "On/Off" switch on the
software Printer Control Panel is changed from "ON" (1) to "0ff" (0), then
an x'0831' POWER OFF sense code is sent to the host immediately.  If it was
the physical printer that was powered off, the indicator in the software
Printer Panel changes to "45".
If the "cancel print" button is pressed on the software Printer Control
Panel, then an x '0811' sense code is sent to the host.

SERIAL PRINTER CABLING CONSIDERATIONS
The following information should be taken into consideration when
installing a serial printer. 1.   Whenever the printer is placed in "HOST"
mode the following signals are turned "ON" (+3 Vdc at      the interface)
and remain "ON" continuously until the printer is returned to "LOCAL" mode:
            Return To Send           (pin 4)
            Data Terminal Ready      (pin 20)
     These pins may be cabled to any pins on the printer as
required/desired (or to nothing).

2.   The serial printer driver interrogates two signals as follows (the pin
numbers are the PC's):             Clear To Send            (pin 5)
            Data Set Ready           (pin 6)

3.   CTS is used for the handshaking protocol (i.e., online/offline, paper
out, etc.).  This pin should      be cabled to whichever pin on the printer
provides this signal.      Novell's SNA products also support the Xon/Xoff
handshaking protocol.  In this case CTS is      assumed to be always "ON"
(provided either by the printer or by strapping the PC's RTS or DTR
(see 1. above) to CTS).  No customization changes are required to support
Xon/Xoff.

     Novell's SNA products do NOT support the "break" handshaking protocol
(available on some printers)!  Any breaks received are ignored.

     Some printers (e.g., GE/Genicom) can be configured to use different
handshaking protocols for different conditions.  For example, a connector
pin for online/offline, X-on/X-off for paper faults, and breaks for other
error conditions.  Novell SNA products do NOT support this!  All error
conditions must be reported via one protocol (either a pin voltage or X-
ON/X-off).

4.   DSR is used to detect printer power on/off.  If the printer provides a
power on signal via a connector pin, that pin should be cabled to the PC's
DSR.

     Not all printers have this feature.  If you are using one that does
not, one of the output signals (see 1. above) should be strapped to DSR.
Not doing this will cause device POWER OFF (sense code x'0831'), as opposed
to INTERVENTION REQUIRED (sense code x'0802'), to be reported to the host
whenever the printer goes offline or runs out of paper.  This is not
catastrophic, but may be undesirable.