OSMKCM06 - SERIAL-PRINTER PROBLEMS IN OS/2 2.1 AND OS/2 2.11
02/06/96

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           Serial-Printer Problems in OS/2 2.1 and OS/2 2.11
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Please Read Entire Document for Full Explanation of Procedures
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DESCRIPTION

* Serial printer does not work.
* Serial printer seems to get too much data (Overflow).
* Serial printer does not print the entire document.


RESOLUTION

Check Operation under DOS
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Connect the printer to the desired COM port; then from real or native 
DOS, try to print. Use either the Print or Copy command. Either use 
Dual Boot or start from a DOS diskette.

If the printer fails to print under real DOS, check the cable, parallel
port, and printer setup.


Determine and Set Handshaking Method
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Modern printers can using handshaking signals to control data flow:

* Software handshaking signals are embedded within the data stream that
  starts and stops the computer when the printer is busy. These signals
  must be interpreted by the application and are slower than hardware
  handshaking.

* Hardware handshaking controls data flow by raising and lowering
  physical signal lines. These signals are called RTS, CTS, DTR, and
  DSR.

The correct handshaking method to use depends on the printer options. 
Older printers usually use switches that are under the printer covers. 
Some new printers have membrane configuration panels for setting 
options. Refer to the printers user's manual, or contact the 
manufacturer, for further details.

Usually, setting the printer object for hardware handshaking is
sufficient. If your printer does not use RTS or CTS handshaking, you 
might try the following combinations:

   MODE COMx RTS=HS, OCTS=ON
   MODE COMx RTS=HS, OCTS=ON, ODSR=ON
   MODE COMx RTS=ON, OCTS=ON, ODSR=ON, IDSR=ON

Note: Always set MODE COMx to ON.


Serial Printers and Plotters--Common Problems and Solutions
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There are very few known problems with using serial printers and 
plotters under OS/2 2.x, other than not having OS/2 driver support. 
The following sections provide information about some of the common 
problems.

  Printer Seems to Be Getting Too Much Data (Overflow)
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  Serial printers use a handshaking protocol. This is either software
  handshaking (XON/XOFF) or hardware handshaking (DSR, RTS, or CTS). If
  the printer is set up for software handshaking, use the MODE command
  to set XON to ON. You might need to set all other settings to OFF. If
  the printer is set up for hardware handshaking, use the MODE command
  to set RTS to HS, OCTS to ON, and ODSR to ON. You also might have to
  set IDSR to ON if the printer uses Data Set Ready (DSR) for
  handshaking. If so, also set ODSR to OFF.

  Printer Not Printing Entire Document
  ------------------------------------
  If you are printing very large jobs, you might need to set the port
  for infinite-write timeout. This is the TO = ON value that is set
  with the MODE command. It is similar to the ",p" value used with the
  DOS 5.0 MODE command. There also might be a handshaking problem.

  Printer Not Working
  -------------------
  Usually a serial printer does not work because the serial
  communication driver (COM.SYS) does not know the handshaking
  method being used.

  Check the product documentation or contact the printer manufacturer
  to determine the type of handshaking the printer uses. A serial
  (RS-232) line tester also is useful.

  Note: If you are printing very large jobs, you might need to set the
        port for infinite-write timeout, as described above.

  If it appears that no data is being sent to the printer, set all MODE
  values to OFF. If the printer then works, set each value to ON to
  determine which setting is preventing transmission to the printer.

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