4 EVOLUTION 1 SYSTEM MANUAL Issue Issue 1.1 20 Dec 2006
/ (0x2f) /
" (0x22) Cents
% (0x25) Solid block
; (0x3b) Ň
? (0x3f) Ě
@ (0x40) Ó
{ (0x7b} Logo 1
| (0x7c) Logo 2
} (0x7d} Logo 3
SOFTWARE PROTOCOL
In the following pages, all references to characters or digits pertain to the
standard ASCII character set. The bar (|) character is used as a field separator
and it is not part of the transferred data. When data is shown in hexadecimal, it
will consist of the hex number preceded by a 0x, for example (0x1B). Generally,
all packets to and from a print station begin with an ESC (0x1B) and terminate
with an EOT (0x04).
There are two types of commands:
Downloading information to the print station
Requesting information from the print station.
To distinguish the two types of commands, a SOH (0x01) is placed after the
command byte in a request command string. The following illustrates this
concept:
To download data to print station
ESC/GROUP ADDRESS/UNITADDRESS/COMMAND/DATA/EOT
To request data from the Print Station
ESC/GROUP ADDRESS/UNITADDRESS/COMMAND/SOH/EOT
NOTE: EACH REQUEST OR COMMAND SENT TO A PRINT STATION
RECEIVES A RESPONSE FROM THAT PRINT STATION. COMMUNICATIONS
SOFTWARE MUST WAIT FOR A RESPONSE TO DETERMINE IF THE PRINT
STATION WAS READY TO ACCEPT THE COMMAND, AND THE DATA WAS
VALID AND PROCESSED. NO RESPONSE COULD INDICATE THE DATA
WAS LOST. IF AN ERROR WAS DETECTED IN PROCESSING A NAK WITH
AN ERROR CODE IS RETURNED.
ERROR CODES
Commands to a print station, if completed successfully, return a single byte
response of an ASCII ACK (0x06). If the command was not successful, a two-
byte response of an ASCII NAK (0x15) is returned, followed by an error code.
Below is a list of the returned error codes.
NAK 1 = NOT USED
NAK 2 = Illegal Command Byte
NAK 3 = NOT USED
NAK 4 = NOT USED
NAK 5 = Trying to write a read only register
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