Tweaking the NT System for some Bi-synchronous Communications Linkages

Sometimes it becomes necessary to make certain adjustments to the NT environment to maximize the performance of the Hayes® OPTIMA™ Business modem when using their AutoSync™ protocol. 

If you are experiencing problems like being knocked-off the line, the connection is being dropped, etc., try this fix:

  1. Click on your START button.
  2. Move your cursor to Settings and click Control Panel.
  3. Find the Ports icon and double click it.  The COM port will show where your modem is.
  4. Click on Settings.  Set the Flow Control to Hardware (not None nor Xon/Xoff)
  5. Then click the Advanced button.
  6. Be sure the FIFO box is enabled (Checked).  Note: in certain rare cases with older 16550 UARTS you may actually have to uncheck this box - but, with newer 16550 UARTS the box should be checked. 
  7. Click the OK button.  Click the OK button.  Click the Close button.
  8. You are done.

In the RAS settings, remove RAS from the particular Com port you are using for the B-Sync modem. 

Another possible way to tweak the NT Operating System...

The NT, like all Windows operating systems, is multi-tasking. NT, Win 95 and Win98 all use PREEMPTIVE multitasking, meaning that the OS periodically decides that an application has had enough time, suspends that application and looks for something else to do. The OS does this even if "nothing else" is running in the background (actually, there are always several applications running in the background, they are part of the OS.)

If you are running the DOS, non-GUI version of the FastSync 3780 program, you could try changing the priority of the DOS session under NT as follows:

Go into Control Panel and click on "SYSTEM". Select the "Performance" tab. Change the slider. You might want to boost the performance of the foreground application (and leave the DOS window in the foreground.)   Make sure that you are NOT using AutoSync1. AutoSync1 is not buffered at the modem, while AutoSync2 is. In theory, AutoSync2 is better suited to transmitting under multi-tasking operating systems.

As a last resort, you may have to lower your block size.  For example, from 512 to 128 (or less).

If all that fails, you will have to contact the manufacturer to find out why your COM port is not buffering data properly.