Read Failed at cupsBackChannelRead

[Zebra]

Hi,

    i changed the program still i having same problem and also i have some questions pls clarify my doubts please sir,

    Question Number 1) the command "/033V/r" Returns the Firmware Version of the Printer i send this code by following way from "filter/rastertolabel.c"


fputs("\033V\r",stdout);
fflush(stdout);
cupsSideChannelDoRequest(CUPS_SC_CMD_DRAIN_OUTPUT, buff, &bufflen,10.0);
bufflen =(int)cupsBackChannelRead(buff, sizeof(buff), 10.0);


In this way the "buff" contains nothing and also "bufflen" is -1.


     Question Number 2) I am sending command to printer from filter for that the printer gives response where i can receive that response.

     Question Number 3) cupsSideChannelRead(-------),cupsBackChannelWrite(----) always return -1.

Thanking you Sir














> If you use stdio you need to fflush(stdout) to force the data to the =
> backend, and then you do NOT want to have a timeout of 0.0 when calling =
> cupsBackChannelRead - use at least 10 seconds to allow for =
> interface/network delays.
>
> For synchronized queries, you probably also want to use =
> cupsSideChannelDoRequest() to tell the backend to drain all pending =
> output before reading the data back, e.g.:
>
>     fputs("something", stdout);
>     fflush(stdout);
>
>     char buff[256];
>     int bufflen =3D 0;
>     cupsSideChannelDoRequest(CUPS_SC_CMD_DRAIN_OUTPUT, buff, &bufflen, =
> 10.0);
>
>     bufflen =3D (int)cupsBackChannelRead(buff, sizeof(buff), 10.0);
>
> On Nov 16, 2009, at 12:57 AM, Zebra wrote:
>
> > Hi,
> >=20
> >=20
> >    I written following code to read the printer response,
> >=20
> > char buff[256] =3D {0};
> > memset(buff,0,sizeof(buff));
> > fputs("\033!RIBLEN\r",stdout);
> >=20
> > memset(buff,0,sizeof(buff));
> > fputs("\033E 2\r",stdout);
> > fputs("\033V\r",stdout);
> >=20
> > memset(buff,0,sizeof(buff));
> > ssize_t retv=3DcupsBackChannelRead(buff,sizeof(buff),0.0);
> >=20
> > Finaly buff contains nothing and return value also -1.pls point out =
> where is error.
> >=20
> >=20
> > Thanking You
> > _______________________________________________
> > cups-ddk mailing list
> > cups-ddk at easysw.com
> > http://lists.easysw.com/mailman/listinfo/cups-ddk
>
> ___________________________________________________
> Michael Sweet, Senior Printing System Engineer
>
>
>