Home/Support/Support Forum/USB to Serial Support Requested
New and improved user forum site coming soon
Welcome to Digi Forum, where you can ask questions and receive answers from other members of the community.

USB to Serial Support Requested

0 votes
We have an application (a microprocessor boot loader) that responds to the PC with a single byte. This is microprocessor dependant and cannot be changed. All of the USB to RS232 adapters that we have tried buffer the incoming data from the micro being loaded with a minimum of 16 bytes. This occurs even when we turn off the “Use FIFO Buffers” in the driver. These adapters work, but due to the delay in sending the microprocessor responses (micro must send 16 responses before they are transmitted to the PC by the adapter) the process that takes less than a minute with an onboard serial port takes several minutes with the adapters. We are looking for a USB to RS232 adapter that will transmit each received byte immediately to the PC as it is received, instead of buffering or delaying it.
asked Apr 21, 2008 in USB Serial by Saminc0 New to the Community (1 point)

Please log in or register to answer this question.

2 Answers

0 votes

Most likely it wouldn't work with any of our Edgeports, even the newer models that have less buffering.

It doesn't surprise me that you're having these problems with USB based serial ports. This type of application (needing timely read/write operations) is best done with onboard serial ports, if possible. You have the ability through Windows to change the FIFO thresholds to 1 byte, etc. Even these (16550 UARTS) will typically have some buffering (16 bytes, etc.) but not nearly as much as a typical USB based serial solution.
answered Apr 21, 2008 by jeremym Veteran of the Digi Community (1,687 points)
0 votes
Thanks for the reply.
answered Apr 22, 2008 by Saminc0 New to the Community (1 point)