Instrument I/O Assistant returning delayed/slow response?

Hi there,
I'm somewhat new to LabVIEW 7.1 - I'm trying to make a simple program that reads and parses data over a serial line then plots it.
I created a small program which connects the output from the IIOA to waveform charts. I've read that the waveform charts plot the data points when the data is received, but when running the program, the chart updates with a new data point at 1Hz, yet my data is being sent at ~10Hz.
I opened the Front Panel for the IIOA and ran just that .vi, and still, the data updates very slowly.
Can someone offer me some insight regarding this problem?
Thank you,
Stefan

Hi Stefan,
If you have opened the front panel for the Instrument I/O Assistant,
and the data still updates slowly, then it is likely that your
instrument is taking longer than you think to respond? I would
recommend that you run NI-SPY while you are performing your
acquisition. In NI-SPY, you can double click on any of the driver
calls and see how long the command took to execute. This will
allow you to determine whether there is a long delay inbetween two
commands, or if the read command is taking a long time to
complete. I suspect that you will see that the read command is
waiting a while before it actually receives the data and is able to
return.
Let us know what you are able to find with NI-SPY, or if you have any more questions.
Jason S.
Applications Engineer
National Instruments

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Troubleshooting slow response to email via vpn

I've just adopted a vpn 3000 concentrator, and am totally learing this, so my apologies.
What could be reasons within a VPN enviroment that people are having slow response to email. (excluding issues with servers)
From a network perspective I can trouble shoot slow response, but how would a vpn enviroment be any more different to troubleshoot.
Naturally VPN is going to be much much slower, but taking 10 minutes for multiple users to get their email seems odd. LAN users get there email within seconds

Hi:
I'll tell you, I used to have the exact same problem at my last company.
We had an Exchange server for email and everyone used Cisco's VPN client.
Email was so slow, it was ridiculous sometimes. Everything else was OK, though. Other applications were OK, and network management was also good. It was just Exchange.
I know that Exchange is notorious for being delay intolerant, but this was bad! and it seemed to get worse with time.
Anyway, I dont know if you have done any troubleshooting yet or not, but you would definitely want to focus on the MTU settings for the VPN connection. Remember that IPSec adds overhead that may cause the ethernet frame to exceed the network's allowable MTU, so the packets get fragmented and reassembled at the receiving end. This can be a very slow process. And some applications are not very tolerant of fragmentation, like SQL and, I think, Exchange, too.
The problem with client VPN is that you would have to adjust each user's PC MTU. With site-to-site VPN, you can, of course, set the maximum segment size of the entire tunnel, so all users sitting behind the tunnel will be forced to conform to the tunnel's stips.
But you can try doing that on a few PCs to see if anything changes. I changed the PCs MTU using freeware called DR. TCP/IP. You can download it for free and it will allow you to change the PCs MTU very easily -- just a few keystrokes, instead of having to go into the registry and get stupid with Windows.
Change the output segment size for the PC to, say, 1400, and see if that improves anything. You would also want to change it on the 3000. I forgot how to do it on the 3000.
Victor

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