Software problem with serial port

[Nike_spb]

Hello! My host is Win 7 64b, Intel Core i5 2400 3.1 GHz, 4 Gb RAM. I have successfully set up serial port on my vm (Win XP 32b) as described in different topics: Port1: Checked Port Number: COM1 (also tried COM2, COM3, COM4) Port Mode: Host Device Port/File Path: COM1 (tried others, see further)

The problem is in connecting to devices via com port. It's not a physical problem, because I've tried to use pci2com controller, usb-rs232 adapter and on-board com port. Settings are: 9600 / 8 / odd / 1 / no flow control. I have to use a monitoring program to log what's happening with com port (see all attachments, except vbox.log). I have used 2 different programs OIL-DS 1.3, T-PDS32 for Windows 2.21. OIL-DS 1.3 always works fine. T-PDS32 doesn't work.

Why is this a virtualbox problem?

1) T-PDS32 works great on any other PC (not virtual)

2) T-PDS32 establishes a connection with a PLC after the settings of the com port have been reset by downloading (or trying to) something via this port by another software - OIL-DS. My guess is that it somehow resets port's parameters and after that T-PDS can work for some time. After reconnecting - again connection problem. See the log file tpds_oil_tpds.txt - there I've tried to connect using T-PDS (no success), then OIL-DS, then T-PDS again (successfully).

3) I've tried to establish the connection with com port using OIL-DS both on host and on vm using exactly the same settings. The behaviour is different (see host_log and vm_log files).

In whole I think that means:

1) it's a software problem

2) virtualbox somehow modifyes the data which is send to com port (and in result some programs can work unstable)

Looking forward to your help. Thank you.

[Nike_spb]

vbox log

[Nike_spb]

Trying to connect using T-PDS - OIL-DS - T-PDS

[Nike_spb]

OIL-DS standart connecting on host

[Nike_spb]

OIL-DS standart connecting on vm