Asynchronous Terminals and Printer Processes Programming Manual

PRINTER PROGRAMMING CONSIDERATIONS
Bell 212A-Type Modems
Unlike the other SETMODE functions, SETMODE 29 remains in effect
after the file is closed. Also, SETMODE 28 does not reset the
modem answering mode to its configured value. Issue SETMODE 29
to set the answering mode at the beginning of each job.
Bell 212A-Type Modems
For all serial printers connected to the host through Bell 212A-
type modems, the receive space disconnect option must be disabled
on the modem at the host end. Otherwise, the ON (space) state of
the BUSY line will force a premature disconnect. If the option
is enabled, the phone answers and then hangs up about 2 seconds
after the printer becomes ready.
ERROR RECOVERY
When using nowait I/O and permitting more than one concurrent
I/O operation, error 100 (DEVICE NOT READY) and errors 200-255
(path errors) require special consideration for all printers. If
several operations run concurrently, it is possible for some to
fail while subsequent ones do not. If this happens, print lines
may be missing or out of order.
DEVICE NOT READY Error
The application process is responsible for handling not ready
and paper out conditions. With some printers, either condition
causes a not ready indication. See the operating manual for your
printer. Typically, if either of these conditions occurs, you
should display a message indicating the condition on the home
terminal. Obtain the logical device number of the home terminal
with the MYTERM procedure. The application process should then
wait for the terminal operator to respond with an indication that
the printer is ready.
Path Errors
Path error recovery on a printer requires some special considera-
tions because of paper movement. Path errors 200 and 201
indicate that the operation never got started. You should retry
the operation.
November 1987 7-39