Unit 3: Interface Specifications
SATO MB200 Operator Manual
PN 9001126A
Page 3-5
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 signalling 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.
MESSAGE FORMATS
SSS, YYT, NNX
Header, variable length
Data, variable length
EXT
BB, CC, CC, Ih
HEADER PACKETS
Connection Request/Connection Response packet
40H
Printer Status Inquiry/Printer Status Response packet
14H
Data Header/Response packet
03H
Data/Data Response packet
15H
Data Transmission Complete/Transmission Complete Response packet
17H
Disconnection Request/Disconnection Response packet
41H
DATA ITEMS
SPACE(13)
Dummy data.
null(4)
Dummy data.
size(4)
Data size.
len(2)
Data block length (maximum 256 bytes).
block
Data block (maximum 256 bytes).
status(4)
Status
id(6)
Printer ID (ASC2 specification).
flag
Packet status flag
