CBM-710/720/730/750User ’sMa nual
27 CITIZEN
9.3 Descriptionof Input/Output S ignals(1) Input/Output Signals
a) RD :
This is the serial signal for received data. When framing, overrun or parity errors occur , the data concerned are
ignored.
b) DTR :
Please write in data or commands when this signal is in a "rea dy"sta te. If written in when in a BUSY state, an
overrun error will occur and the data will be ignored. Data can be written into t he input buffer even during
printing. Further, a BUSY signal is gene rated when the power is turned on, while test printing, when
ONLINEE and during reset.
c) FAULT :
When there is a prob lem in the printer mechanism the FA ULT signal will b e issued, and all cont rol circuits wi ll
be interrupted. To RESE Tt his signal, first correct the cause of tro uble in the printer mechanism. Then, by
pressing the LINE switch or by inputting "0" (LOW LEVEL) at the RESET terminal, the FAULT can be
cleared.
Causesof the FAULT signal are lack of paper and errorsin the printer mechanism. Printererrors include such
as, the print head stopping durin g print operation or fa ilure of the print head to re turnto the home position.
d) RESET:
This signal resets the entire printer.
e) PE :
This signal is output when the paper roll is nearthe end.
f) TD (Valid only fo r type B):
When receiving data signals, and when the printer's input buffer has less than 1K bytes remaining open, the
DC3 code (13H) is issued, indicating that receipt of data is not possible. When the data in the input buffer is
reducedto 2K bytes, the DC1 (11H) code is issued, which indicatesthat data receip t ispossible.
g) FG:
Frame Ground
h)GND:
Commonground for all circuits.