Citizen Systems 291 - Manual (Page 36)

CBM-290/291 User’s Manual
22 CITIZEN
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)
[Printer side] [Host side]
Output (DTR, TXD)
RXD
Mark = (
−
8V) : Stop bit
Space = (+8V) : Start bit
MAX 232 equivalent
Mark = (
−
8V) : 1
Space =(+8V) : 0
TXD
(
−
8V) : When busy Space
(+8V) : When ready
DTR
MAX 232 equivalent