Citizen Systems CBM-253 - Manual (Page 39)

CBM-253 User’s Manual
27 CITIZEN
(2) DTR
When the DTR/DSR control has been selected, data or commands should be written when this signal is at
ready. If writing is carried out while this signal is at BUSY, an overrun error will occur and the data will be
ignored. Data can be written into the input buffer even when printing is being carried out.
(3) T X D
When receiving data while using Xon/Xoff control, an Xoff (13H) 'Data receiving not possible' signal will be
output when the remaining space of the input buffer inside the printer becomes less than 10 bytes. When the
input buffer remaining space become more than 20 bytes, an Xon (11H) 'Data receiving possible' signal will
be output. When sending status information while the DTR/DSR control is selected, confirm that the DSR is
at 'space' before sending the data. In the Xon/Xoff control, the data should be sent regardless of the DSR
condition.
(4) FG
This is a frame ground.
(5) SG
This is the common ground on the circuit board.
Receiving control
When DTR/DSR control has been selected, data will be received from the host when the DTR signal is at
'space' . Data receiving will not be possible when the DTR signal is at 'mark'.
When Xon/Xoff control has been selected, data will be received from the host side after the Xon signal has
been sent. However, data receiving will not be possible after the Xoff signal has been sent.