"R. Glenn Givens" <[EMAIL PROTECTED]> wrote: >I am writing a data link to communicate between a PC running LV 6.0.2 and an >industrial computer. The link on RS232C will run @ 9600 baud and the >throughput is such that I'm using 1/4 to 1/3 of capacity. The industrial >computer sends the data and has a 500 byte buffer each for send and receive. >But the data is all one way from the industrial computer to the PC. The PC >will save this data to disk continuously and also present displays etc. > >It sounds like there are many ways to operate the serial port in LV (maybe >VISA, maybe direct port manipulation, more likely old-fashioned serial port >VI's?. I haven't done much checking but I wondered what the consensus was >for the best method for this type of application. Since PC's only have a >buffer of a few bytes, I would prefer to have something automatically handle >the interrupts and have a big input buffer that I just read from time to >time (say every 50 to 100 msec). I used to do that interrupt handler stuff >in assembler in the DOS days.
VISA does all the buffering for you. You just open a session and with 9600 baud you shouldn't even need to configure special buffer sizes. I use VISA with up to 48kBaud regularly without any problems and have also managed with quite some ease 115kBaud on VISA. There is really no need to do direct register programming and interrupt handling on application level anymore for standard serial port communication. VISA and similar interfaces neatly deal with this for you and you do absolutely not need to worry about that. It may be hard to get used to this if you have previously dealt with these thngs yourself but believe me it is a big relieve. The serial port problems are seldon on the VISA (or whatever API you use) level but most often on the actual instrument-application communication level, due to funny (not to say stupid) protocol conventions and most often bad documentation. Rolf Kalbermatter CIT Engineering Nederland BV tel: +31 (070) 415 9190 Treubstraat 7H fax: +31 (070) 415 9191 2288 EG Rijswijk http://www.citengineering.com Netherlands mailto:[EMAIL PROTECTED]
