IBM 4685-L0D Setup, Operation, And Service Manual page 53

Hardware-flow operating mode
In the hardware-flow operating mode, the conditions are as follows:
On receiving a DTR signal, the scanner establishes a connection with a POS
terminal, and then enters the ready state.
The scanner decodes the labels immediately after power-on.
The scanner buffers one additional label, if desired.
The scanner sends the RTS signal and then requests that the decoded data
from the label be sent to the POS terminal.
The POS terminal controls the transmission of the decoded data by means of
the software control handshaking characters, XON/XOFF.
The scanner applies the intercharacter delay specified in the configuration.
Hardware-flow operating mode with timing and flow control
The handshake timing and flow control used is RTS/CTS. The hardware-flow oper-
ating mode operates as follows:
The scanner decodes a label. If you have chosen beep/lamp option 1, the
scanner beeps and the lamp comes on. (For a description of that option, see
page 4-16) The RTS signal is sent to the POS terminal as a notice that the
decoded label data is ready for transmission.
The scanner monitors the CTS input signal to determine whether the POS ter-
minal is ready to receive data. If the CTS signal is active, the data decoded
f4rom the label is transmitted. If the signal is inactive no data is transmitted. If,
during data transmission, the CTS signal goes from active to inactive, the data
transmission is suspended. It is resumed only after the POS terminal resends
the CTS input signal.
After the last character is transmitted, the RTS signal is resent. If you have
chosen beep/lamp option 2, the scanner beeps and the lamp comes on.
Another label is decoded, to begin a repetition of the cycle.
For details of the hardware-flow operating mode, see Figure 4-3.
Chapter 4. RS-232 Scanner interface specifications
4-9