Printronix P9000 Series - Manual (Page 177)

7-7 Interfaces
Data Terminal Ready (DTR) - Control signal from the printer. Subject to configuration.
RS-232 Serial Interface Protocols
The following serial interface protocol characters are available. The protocol can be confiĆ
gured from the control panel to meet host interface requirements.
X-ON/X-OFF - The printer transmits an X-ON character (hex 11) when entering the on
line state or when the buffer is almost empty. The printer transmits an X-OFF character (hex
13) when entering the off line state or when the buffer is almost full.
DTR (Data Terminal Ready) - Control signal from the printer. (Subject to configuration.)
Configurations include: always true, always false, true if on line and buffer not full, and true if
off line or buffer almost full. When the printer is off line, or when its buffer is almost full, DTR
is toggled. When the printer is ready to receive data, DTR is toggled back.
ETX/ACK - With ETX/ACK protocol selected, the printer interface operates in a block strucĆ
tured mode. The host sends a block of data in response to an ACK character (hex 06) sent from
the printer. The host marks the end of the block of data with an ETX character (hex 03). When
the printer recognizes the ETX character, the printer prints the data block and checks the
space available in the buffer. If space is available for the next block of data, the printer sends
ACK to the host. If space is not available, the printer withholds ACK until sufficient space is
available.
ACK/NAK - With ACK/NAK protocol selected, the printer responds as described for ETX/
ACK protocol except the printer monitors the received data for parity error. If a parity error is
detected, a NAK character is transmitted to the host upon receipt of the ETX character. The
host is expected to repeat the data transmission.
RS-232 INTERFACE ERROR - With an odd or even parity check in effect, an erroneous
character shall be replaced with a question mark (?). If a parity error is detected, a NAK charĆ
acter (hex 15) is transmitted to the host when the ACK/NAK protocol is selected. When parity
is not checked, parity errors are ignored and the characters are printed as received. Parity
checking is a configuration option selected from the control panel. When a framing error ocĆ
curs, an exclamation point (!) will be printed. When a data overrun error occurs, an asterisk (*)
will be printed. After 20 successive errors have been received, a line feed is added which forces
printing to occur.
RTS (Request To Send) - Control signal from the printer. Subject to configuration. Refer to
DTR above for detailed configuration actions.
Reverse Channel (RC) - Control signal from the printer. Subject to configuration. Refer to
DTR above for specific configuration actions. (Reverse Channel is not an official RS-232C
signal; it is included for compatibility with earlier Printronix products.)
RS-232 Serial Interface Configuration
The printer is configured at the factory according to the specified interface as shown in the
Configuration chapter. However, the interface configuration parameters can be changed. The
following configuration parameters can be verified or changed as necessary to meet specific
application requirements: