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I have an application that sends and recieves data from a power supply and on most computers (desktop PCs), the application runs fine. I found that on at least one computer, using a Keyspan Tripp Lite USB to RS232 adapter, in one out of 25 queries, I wasn't getting the whole reply back from the instrument. After some debugging I found out if I switch the VISA write and read calls from synchronous to asynchronous I don't see the error any more. Is there a way to disable asynchronous mode for that computer? I'd rather not have to find all the VISA write calls in my application and update each one just to support that computer.
Try playing with the Tx ACK Advance setting on that port first. (From the Keystone config utility) You might also look into the Rx FIFO buffer settings (16 is a short default buffer)
There is no (Easy) way to universally disable Async . VISA Async tranfers MAY complete synchronously anyhow (It throws a warning when that happens) So if Keystone settings do not help you might want to swap out to a FTDI chip enabled USB - serial device.
