TransAct Epic Edge, Руководство по интеграции OEM

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10-Enhanced Features Epic Edge™ OEM Integration Manual
100-14444 Rev B August 2018 Page 173
Data Packet Protocol (with CRC)
The Epic Edge™ can be configured to implement a packet protocol with a cyclical
redundancy check (CRC) for verifying data integrity.
This packet protocol is a raw data encapsulation protocol which can be enabled or
disabled. The native emulation/command set is used, and any amount of data
(determined by the host) up to 4KB at a time can be encapsulated to provide verification
of the data’s integrity.
This packet protocol has:
•
Start of record character
•
Two byte length; up to 4096 bytes of data per packet are allowed
•
Sequence number
•
End point ID (reserved for future use)
•
16-bit CRC
Format
[Start] [Length] [Sequence number] [Endpoint ID] [Data …] [CRC]
Start is a one byte code that = 0xff;
Length is a two-byte length of the entire packet to be transmitted, specified with the high
byte first, followed by the low byte.
Sequence number is checked for and must be 1 + the last sequence number. The valid
range is 0 through 7, and then the count restarts at 1.
Endpoint ID should be 0 for normal operation. If the endpoint is 1, then the sequence
number is ignored. Use an endpoint of 1 to send a reset to the printer when
communications are out of sequence.
Note:
If communications are out of synchronization, you may need to send the reset more than
once (in separate packets) to get re-synchronized.
Data is the raw data sent to the printer (i.e. printer commands).
CRC is the 16-bit cyclical redundancy check specified with the high byte first, followed by
the low byte. This value is compared to the value calculated by the printer, and an error
is generated if it does not match. The CRC is calculated using the entire packet
(excluding the CRC bytes).
Examples:
Send the characters “5678” (print “5678”)
<0xff> <0x00> <0x0b> <0x01> <0x00> 5 6 7 8 <0xc5> <0x06>
Send “Hello There [cr][lf]” (print “Hello There” and line feed)
<0xff> <0x00> <0x14> <0x01> <0x00> “Hello There” <0x0d> <0x0a> <0xc0> <0x94>
Send “[gs]~PTVoid.lay^^” (print layout command)
<0xff> <0x00> <0x15> <0x01> <0x00> <0x1d> “~PTVoid.lay^^” <0x84> <0x93>