Citizen Systems CBM-290 - Manual (Page 31)

CITIZEN 31
7.5 Data receiving control
When DTR/DSR control having been selected, with BUSY signal at "LOW", data from the
host side are received. With the signal at "HIGH", they can not be received.
When DTR/DSR control not having been selected, after X-ON transmission, data is
received from the host side. No transmission of data can take place after X-OFF is
transmitted.
7.6 Buffering
Data transfer to the input buffer include DTR signals and TD signals as the control signals
concerned.
(1) DTR signals (See 7.2. (2).)
(2) TXD signals (See 7.2. (3).)
7.7 Electrical characteristics
(1) RS-232C Circuit
Input (RXD, DSR)
RXD Mark = (-8V) : Stop bit
MAX 232 equivalent Space = (+8V) : Start bit
Output (DTR, TXD)
MAX 232 equivalent
DTR (-8V) : When busy TXD Mark = (-8V) : 1
(+8V) : When ready Space =(+8V) : 0