Wincor Nixdorf TH210, Руководство программиста

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TH210 Programmer’s Guide
70
In this case the printer will use the real time command sequence bytes instead of the other
command’s parameter bytes when finally executing that other command from the buffer; the
other command will NOT be executed correctly.
These three situations generally preclude use of standard DOS drivers for the serial communication
ports when using real time commands.
Moving data through the buffer
Applications should not let the buffer fill up with real time commands when the printer is busy at
the RS-232C interface. A busy condition at the RS-232C interface can be determined by bit 3 of the
response to 1D 05, or 1D 04 1, or 10 04 1. The reason for a particular busy condition can be
determined by other responses to 1D 04 n or 10 04 n.
Although the printer responds to real time commands when it is busy, it will place them into the
buffer behind any other data there, and flush them out in the order in which they were received.
When the printer is busy due simply to buffer full (that is, it can’t print data as fast as it can receive
it), then data continues to be processed out of the buffer at approximately print speed and the real
time commands will eventually get flushed out.
When the printer is busy due to an error condition, then data stops being processed to the buffer
until the condition clears one way or another. In either case, but more quickly in the case of an
error condition, the buffer can fill with real time commands.
When the DLE (0x10) sequences are being used, the last byte stored when the buffer fills up could
be the DLE (0x10) code, with no room for the subsequent EOT or ENQ. When this lone DLE (0x10)
byte is finally processed out of the buffer it will be interpreted as a clear printer command.
Similarly, when the GS (1D) sequences are being used, the last byte stored when the buffer fills up
could be the GS (1D) code, with no room for the subsequent EOT or ETX or ENQ. When this lone GS
(1D) byte is finally processed out of the buffer it will use the next byte, whatever it is, as the
second byte in its GS (1D) sequence.
To guard against this situation, the application must determine the cause of a busy condition and
take appropriate action or pace the real time commands to avoid filling the buffer. There is a
minimum of 256 bytes available in the printer’s buffer when it goes busy.
Busy line and fault conditions
If the printer is in error condition (cover is open, paper is exhausted…), the printer will still accept
data, respond to the batch mode status commands (1B 76 and 1B 75 0), handle the cash drawer
commands, and not go busy until it actually tries to execute a print command. Then it will stay
busy and stop processing data out of the receive buffer until the condition clears. It will respond to
the real time commands as described below.
Real time status transmission
GS sequence DLE sequence
ASCII
Hexadecimal
Decimal GS EOT n
1D 04 n
29 4 n
DLE EOT n
10 04 n
16 4 n
Value of n : GS/DLE sequence
1 = Transmit printer status
2 = Transmit RS-232C busy status
3 = Transmit error status
4 = Transmit receipt paper status