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

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Characteristics
This section describes the following characteristics of the RS-232 scanner interface:
Interface signals
Signalling characteristics
Device requirements
Voltage and current requirements
Interface signals
The RS-232 scanner interface handles the following interface signals:
Signal ground
A reference signal, which establishes a common reference point for all
signals.
Data set ready (DSR)
A control signal, which the POS sends to the scanner to notify it that the
POS terminal is connected to the communication channel and is ready
for operation.
Data terminal ready (DTR)
A control signal, which the scanner sends to the POS terminal to notify it
that the scanner is in the active state–that is, powered on and ready to
communicate.
RXD data
A data signal, which the POS terminal generate and sends to the
scanner on a dedicated circuit.
TXD data
A data signal, when the scanner generates and sends to the POS ter-
minal on a dedicated circuit.
Request to send (RTS)
A control signal, which the scanner issues when it is sending a message
or has one ready to send.
Clear to send (CTS)
A control signal, sent to the scanner to control the following:
Transmitting data from the scanner to the POS terminal
Operating the beeper and the lamp
Enabling or disabling decoding of labels
Chapter 4. RS-232 Scanner interface specifications
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