[Info-vax] Timeout in a write using QUIW.

[Phil Howell]

On Thursday, 22 June 2023 at 10:06:02 pm UTC+10, Jan-Erik Söderholm wrote:
> Den 2023-06-22 kl. 13:25, skrev Phil Howell: 
> > On Thursday, 22 June 2023 at 7:36:54 am UTC+10, Jan-Erik Söderholm wrote: 
> >> Den 2023-06-21 kl. 23:25, skrev Stephen Hoffman: 
> >>> On 2023-06-21 20:45:12 +0000, Jan-Erik S derholm said: 
> >>> 
> >>>> Now, here is a technical one... 
> >>>> 
> >>>> When doing a *read* from a terminal device using QIOW, one 
> >>>> can use IO$M_TIMED and supply a timeout value in P3. That 
> >>>> works perfectly and we use that a lot... 
> >>> 
> >>> I've never had great success... 
> >> 
> >> 
> >> I'm sorry about that. As I wrote, it works perfectly. In the 
> >> case of reads, of course, where it is supported. 
> >> 
> >> My question was about writes, and it has been confirmed that 
> >> timeout paramaters are not supported there. Thanks Arne. 
> >> 
> >> Now we need to weight the coding work against getting 
> >> network cables installed to the printers. Wired printers 
> >> will also "solve" the issue with the current code. We have 
> >> 15-20 older similar Zebra label printers, all wired, and 
> >> we do not see these error scenarios with those. 
> >> All using the same C routine for the QIOW calls. 
> >> 
> >> 
> >> Jan-Erik. 
> > While you cannot request a timeout on a WRITEVBLK 
> > you may be able to workaround this by using READPROMPT 
> > With this you get two i/o's in one call, 
> > the first is a write of your "prompt" followed by a read on the same channel. 
> > If you set up your "prompt" as the content of your label then do the qio call 
> > it should write this to the device, then do the read, which you can check or ignore. 
> > If you get a tt_timeout, then wait a bit and retry. 
> > The most concise explanation of this is in wikipedia on the qio page. 
> > The I/O user manual just goes on and on 
> > You may have to increase the size of the typeahead buffer to cater for the size of your label 
> > as well as managing all the usual qio stuff like buffer lengths, IOSBs, terminator masks, ASTs, etc. 
> > 
> > If I was retiring in a couple of weeks I would recommend cabling up all the printers, 
> > but it could be an interesting way of getting your successor to hate you? 
> > 
> > Phil 
> > 
> >
> Hi. That was a nice way of "using" (or "mis-using" ? ) QIOW! 
> I'm actually leaving this place Friday next week, 30 June. 
> 
> Right now, it seems as we'll simply get the printers hard-wired. 
> It is 6 printers that are on Wifi now, and our other 15-20 label 
> printers (all hard-wired) do not show the same error scenario. 
> 
> Jan-Erik.
That does seem the more expedient solution.
Of the regular posters here, you must be one of the few that has
a real live job running VMS, so I'm sorry to see another one go,
soon it will only be retirees, hobbyists, consultants and contractors here.
Funnily enough I have a long history with label printers,
firstly on VAX with LA75 used with VT. terminals as  "slave" printers,
then high speed Zebra printers for long print runs.
On Alpha we used various brands with varying success but eventually
standardised on "Blaster Advantage" RJ45 networked printers.
These were expensive, but pretty rugged and reliable
These printers also were able to interpret the Zebra language (ZPL)
so our label print files were about 8 lines of ascii test sent via telnet.
Barcodes and QR codes were able to be added easily as the printer did all the work!
Phil