TA Triumph-Adler LP 4140 - Manual (Page 159)

Computer Interface
ADVANCED OPERATION GUIDE 5-9
PRESCRIBE FRPO D0 command
The PRESCRIBE FRPO D0 command provides control over XON/XOFF
operation when an error occurs on the serial interface. The following table
summarizes the error status corresponding to different D0 values.
Timing of XON transfer to host
while Ready or Waiting
Serial interface error
Error
not resolved
Error
resolved
XON sent every 3 to 5 seconds D0=0
(default) D0=1
XON not sent D0=10 D0=11