ENET 232 pauses between groups of characters

[LarryVatterrodt]

Can the ENET 232 send out characters (large binary file) at a steady stream without long (~1sec) pauses every ~100 characters, or is it only intended as an instrument control with short strings?

[DarylE]

Hello,

Since you are writing a large amount of data one thing to do is to set the write mode to synchronous for your VISA Write VI by right clicking on the VI and choosing Synchronous I/O Mode>>Synchronous.  This will help when transferring large amounts of data because it will lock the process thread for longer periods of time that are performing the write.  The difference between synchronous and asynchronous VISA transfers can be found at The Effect of Asynchronous and Synchronus VISA Reads and Writes.  Another factor to consider is the FIFO buffer for the ENET-232 which is 128 bytes (Much larger than the built on serial ports of a mother board).  With a VISA write it will take the data you want to write from RAM to the FIFO of the ENET-232, when the FIFO is full it will then cause an interrupt to empty the FIFO by outputting the data on the port.  This is also described in The Effect of UART FIFO Sizes in Serial Application Performance.

Daryl E
Applications Engineer
National Instruments

[JasonSmith]

Hi Larry,

I would not expect you to see delays such as this with your ENET-232 device.  To verify this, I performed a test sending a string of 10000 characters, which completed in less than a second at 115.2 kbps using a ENET-232/4.

Like any ethernet device, the performance of your ENET-232 is going to be dependant on the network traffic of your system and your network.  In troubleshooting this issue, you may want to try connecting your ENET-232 directly to your computer with a crossover cable (You will need to reconfigure your machine and ENET-232 for static IP addresses for this to work), in order to eliminate the effects of any other network traffic in your area.

If you still see these delays, produce a small application which can be used to demonstrate the problem you are seeing, and I would be happy to try it here on my system.  This example should not be dependant on any external instruments, as I would not have them available.

Let us know what you find out,

Jason S.
GPIB & Serial
National Instruments

[LarryVatterrodt]

Thanks for the responses.  I did find that the delays are only when I sent a file out using HyperTerminal.  I wrote a small routine to send a file using ViWrite, and had no delays at all, which is a good solution for our application.

Thanks.