CommMG timing while using 2 connections

[Myicq]

I have been using the excellent CommMG for a long time. Always happy with performance.

Today I have been using two different connections: one for a digital I/O board, and another for sending data.

I time the communication using high precision "QueryPerformanceFrequency". I could not understand a difference between my settings and the measured timer.

Using debugging I found that this code would take approx 70..100 msec - or about 35 msec each.

; --- select the I/O connection to trigger
_CommSwitch(1)
_CommSendstring("1")
_CommSendstring("Q")
; --- select the data connection to send data
_CommSwitch(4)
_CommSendstring("XYZ")

while without the _CommSwitch() the code block would take < 2 msec.

I tried with the 64 bit version of CommMG as well. No difference.

This may all be due to Windows functions being slow, and probably can't be improved ?

Is there a way to avoid commswitch, such as using two instances of something - my experience is not enough to suggest what. In Delphi, I would have used two instances of a connection.