Printronix L5020 - Manual (Page 225)

RS-422 Serial Interface
227
RS-422 Serial Interface Signals
The RS-422 serial interface signals are defined below.
Received Data (RxD) - Serial data stream from the host to the
printer.
Transmitted Data (TxD) - Serial data stream from the printer to the
host. Subject to protocol selection.
Request To Send (RTS) - Control signal from the printer to request
permission to send data to the host. Subject to configuration.
Clear To Send (CTS) - Status signal to the printer indicating the
host is ready to receive data/status signals from the printer. When
CTS is enabled, DSR and CTS must both be asserted for the
printer to transmit flow control characters to the host.
Data Set Ready (DSR) / Clock B - Status signal to the printer
indicating the host is in a ready condition. DSR is ignored unless
CTS is enabled.
Data Terminal Ready (DTR) - Control signal from the printer to the
host. When enabled, the host activates the data channel. Subject to
configuration.
Clock Signal B - External timing for signals on data channel B.