Data Reception Control; Buffering; Connections To Serial Port - Citizen BD2-1220 User Manual

7.6 Data Reception Control

When the DTR/DSR control mode is selected, host data can be received if the DTR signal is at Space, while
it is not receivable if the signal is at Mark. When the DTR/DSR control mode is deselected, host data can be
received after XON is transmitted, while it is not receivable after XOFF is transmitted.

7.7 Buffering

Data transfers to the input buffer are controlled by the DTR and TD signals. The input buffer has a 4K-byte
capacity, so the host is freed immediately after data transfer completes.
(1) DTR signal (Refer to 7.2 (2))
(2) TD signal (Refer to 7.2 (3))

7.8 Connections to Serial Port

(1) Connections to the 25-pin/9-pin serial port
CN1
20
21
22
23
3 (4)
Note: The diagram above is a typical connection to the host. When inline cable connection is required, the
DTR/DSR and RD/TD lines must be reversed each.
(2) Connections to other parallel port
When connecting to other parallel port, carefully check the signal names and their destinations, and establish
correct connections.
25-pin serial interface
DTR DSR
6
TD RD
3
RD TD
2
DSR DTR
20
GND GND
7
CN1
DTR
20
TD
21
RD
22
DSR
23
GND
3 (4)
20
BD2-1220/1221 User's Manual
9-pin serial interface
DSR
6
RD
2
TD
3
DTR
4
GND
5