Protocol Mode - Infinite Peripherals DPP-450 User Manual

PROTOCOL MODE

Protocol mode is active when hardware switch 11 is on. The purpose of this
mode is to give stronger real time access to the printer. All input data are sent
in packets as described below. The printer returns an answer to the packet
immediately
.
Output packet format: Channel Command LenHi LenLo Data
Answer format: Channel Status LenHi LenLo Data
Channel: One byte:
Bits 0 – 6 Channel number (Device type)
Bit 7 0: Send data; 1: Response
Command: One byte with possible value:
0: Open channel (No action – all channels always open)
•
1: Close channel (No action – all channels always open)
•
2: Send data
•
3: Request data
•
>4: Application specific
•
Status: One byte:
Bit 0
Bit 1
Bit 2
Bit 3
Bit 4
Bit 5
Bit 6
Bit 7
Bit 7 is set, if:
There are unprinted lines in the print buffer.
•
There are bytes in the print buffer.
•
The printer is executing a macro.
•
The printer is executing self test
•
The button <LF> is pressed – feeding paper.
•
LenHi: High byte of data length of data. 00h to 08h.
LenLo: Low byte of data length of data. 00h to FFh.
Data: 256*LenHi +LenLo data bytes.
The maximum packet length is 2048 bytes.
The answer differs from the command by bit 7 (MSB) in the channel number. If bit 7 is 0 then it
is a command, if it is 1 then it is a response. Bit 0 in the status byte shows if there was an error
accepting or processing the data block. If this bit is 1 the other bits show the type of the error.
The printer never issues a transmission by itself. It always responds as an answer to a command.
The communication goes like this:
Host – command, Printer – answer; Host – command, Printer – answer; etc.
0
No error
ACK (Packet accepted)
Channel and command OK
Battery OK
Printing head OK
Paper OK
Printer ready
Error occurred
NACK (Packed not accepted)
Wrong channel or command
Low battery
Printing head too hot
Out of paper
Not defined
Printer busy
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