All Interfaces; Receive Buffer; Ack/Nak Protocol; Status4 Return - SATO LC400e Series Operator's Manual

7.7 ALL INTERFACES

This section contains information that is applicable to all interface types offered.

7.7.1 Receive Buffer

The data stream is received from the host to the printer one job at a time. This allows the software program to
maintain control of the job print queue so that it can move a high priority job in front of ones of lesser
importance.
A multiple job buffer allows the printer to continuously receive print jobs while compiling and printing other jobs
at the same time. It acts much like a Print buffer to maximize the performance of the host and the printer.
The printer receives and prints one job at a time. If a print job exceeds the buffer size, transmission will be
rejected by the printer. Flow control protocols to throttle transmission are not used. Error conditions that occur
during the Print Data transmission will cause the printer to return a NAK.

7.7.2 ACK/NAK Protocol

Bi-Directional ACK/NAK protocol is used for error control. In a normal transmission sequence when the
transmission is received, the printer will return an ACK (06H) signifying that it was received without a
transmission error. After the transmission command structure has been analyzed, a status byte is returned to
the host. This status byte informs the host of the validity of the command structure.
If the command structure is error free, the printer proceeds with the print operation. When the print operation
is completed, a Printer Status message is returned to the host. If an error was detected during the initial
transmission sequence, a NAK (15H) will be returned signaling to the host that the received transmission
contained errors and must be resent. If the returned Status byte indicates a command structure error, the error
must then be corrected before the print data is resent to the printer.
A valid transmission to the printer must be bounded by an STX/ETX pair, with the STX (02H) signifying the
start of the Print Data and ending with an ETX (03H) signifying the end.

7.7.3 Status4 Return

This communication protocol is designed for the purpose of monitoring and controlling print data status in the
host and featuring various functions.
PIN DIRECTION
1 Reference
2 To host
3 To printer
7 Reference
LC400e Series Operator Manual
INTERFACE SIGNALS
FG (Frame Ground)
TD (Transmit Data) - Data from the printer to the host computer.
RD (Receive Data) - Data to the printer from the host computer.
SG (Signal Ground)
Section 7: Interface Specifications
SIGNAL DEFINITION
Page 7-15