MSComm and a Scanner
in [Visual Studio]
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From: Jim Mack on 2 Dec 2006 10:28 J French wrote: > > Maybe the RS232 is really running through a network and there is some > sort of buffered timeout on the send side. > > I've seen similar stuff with printers taking an age to start. Could be, but I'm skeptical. We'd need to know how the scanner is connected and if the behavior occurs when the scanner is directly connected to the PC. Either way, the OP's understanding of how MSComm operates is not complete, since it does not on its own initiate conversations. Whatever this is, it's more likely to be at the scanner end than at the PC end. If the PC were blindly reading every 3-4 minutes, you'd expect a large variation in response times since the scanning and the reading would not be synchronous -- a scan would sometimes occur right before a read, and sometimes right after one. -- Jim
From: Henning on 2 Dec 2006 10:56 "Jim Mack" <jmack(a)mdxi.nospam.com> skrev i meddelandet news:Jb-dnQbcj-QUBuzYnZ2dnUVZ_u-dnZ2d(a)comcast.com... J French wrote: > > Maybe the RS232 is really running through a network and there is some > sort of buffered timeout on the send side. > > I've seen similar stuff with printers taking an age to start. Could be, but I'm skeptical. We'd need to know how the scanner is connected and if the behavior occurs when the scanner is directly connected to the PC. Either way, the OP's understanding of how MSComm operates is not complete, since it does not on its own initiate conversations. Whatever this is, it's more likely to be at the scanner end than at the PC end. If the PC were blindly reading every 3-4 minutes, you'd expect a large variation in response times since the scanning and the reading would not be synchronous -- a scan would sometimes occur right before a read, and sometimes right after one. -- Jim Agree, and most scanners first do a scan to calibrate, then the final scan. The scanning can take more than that time to complete. /Henning
From: Henning on 2 Dec 2006 10:57 "Henning" <computer_hero(a)coldmail.com> skrev i meddelandet news:4571a25d$0$36418$57c3e1d3(a)news3.bahnhof.se... > > "Jim Mack" <jmack(a)mdxi.nospam.com> skrev i meddelandet > news:Jb-dnQbcj-QUBuzYnZ2dnUVZ_u-dnZ2d(a)comcast.com... > J French wrote: > > > > Maybe the RS232 is really running through a network and there is some > > sort of buffered timeout on the send side. > > > > I've seen similar stuff with printers taking an age to start. > > Could be, but I'm skeptical. We'd need to know how the scanner is connected > and if the behavior occurs when the scanner is directly connected to the PC. > > Either way, the OP's understanding of how MSComm operates is not complete, > since it does not on its own initiate conversations. > > Whatever this is, it's more likely to be at the scanner end than at the PC > end. If the PC were blindly reading every 3-4 minutes, you'd expect a large > variation in response times since the scanning and the reading would not be > synchronous -- a scan would sometimes occur right before a read, and > sometimes right after one. > > -- > Jim > Agree, and most scanners first do a scan to calibrate, then the final scan. > The scanning can take more than that time to complete. > > /Henning > > Ooops, that was not a flatbed scanner. ;) /Henning
From: Dave on 2 Dec 2006 23:45 Thank you all for your informative and prompt replies! Your information is very valuable in that I'm somewhat of a rookie here. My code writing abilities are strong enough to keep the big guys happy, but my knowledge of hardware connections is very limited. Here are the specs: Out in the shop we have a Symbol brand "Hotshot" scanner hooked to a PSC PowerWedge, hooked then to an ICPCON model i-7188E1 Internet Communication Controller (a little blue box the size of a pack of cigarettes) that is hooked up to the ethernet. Then it goes to the hub and then my PC. I can't show you my code right now 'cause I'm at home and my code is at work. BUT....I still do not think this is a code issue. All I did was put my code into an MSComm event (like a control button's click event) and send the Scanned string to an Access database. What I am trying to figure out is why it takes 3 minutes for the scanned string to get to the form's textbox. Thank you again for your informative input. Dave
From: NewsGroup on 3 Dec 2006 05:05
I have experienced a delay with MSComm when inputlength is set to zero. This should result in no buffering but with USB-RS232 converters this ends up as a buffer length of 65536 and a long delay as a result. Worth a try. Mike. "Dave" <davegp2(a)msn.com> wrote in message news:1165121145.782616.127460(a)80g2000cwy.googlegroups.com... > Thank you all for your informative and prompt replies! > > Your information is very valuable in that I'm somewhat of a rookie > here. My code writing abilities are strong enough to keep the big guys > happy, but my knowledge of hardware connections is very limited. > Here are the specs: Out in the shop we have a Symbol brand > "Hotshot" scanner hooked to a PSC PowerWedge, hooked then to an ICPCON > model i-7188E1 Internet Communication Controller (a little blue box the > size of a pack of cigarettes) that is hooked up to the ethernet. Then > it goes to the hub and then my PC. > I can't show you my code right now 'cause I'm at home and my code is at > work. BUT....I still do not think this is a code issue. All I did was > put my code into an MSComm event (like a control button's click event) > and send the Scanned string to an Access database. What I am trying to > figure out is why it takes 3 minutes for the scanned string to get to > the form's textbox. > > Thank you again for your informative input. > > Dave > |