Question: I am using VSP with On-the-fly commands. The Device Server initiates the connection when it receives the data from its serial port. Sometimes I see garbage data among first bytes received by the VSP. Why?
Answer: On-the-fly commands change the operating parameters of the serial port. To put required change into effect, the Device Server must close the serial port first, make the changes, then reopen the serial port. Naturally, this may cause some incoming serial port data to be lost while the serial port was in the closed state.
You may experience this problem if the Device Server starts receiving the serial data into its serial port and, as a result, establishes a connection to the Virtual Serial Port of the PC. If on-the-fly commands are enabled on the VSP, the latter will send a batch of such commands as soon as the incoming connection from the DS is accepted. If the serial data continues being received on the serial port of the DS at that time you will have missed or corrupted data fragment.
This is the reason why the Connection Wizard pre-selects “disable on-the-fly commands” when you specify that the connection between the DS and the VSP will be initiated by the “Device Server” or “Any side”.
