The same Delphi CS program has two credit card data to read the COM interface, one can, another without prompt connection is successful, a credit card is invalid, consult,

CodePudding user response:

Serial port has occupied, such as: A and B interface, A interface to open the serial port connection equipment, B interface connection device for A serial port has occupied again, CreateFile (open) will fail,

CodePudding user response:

The COM is exclusive, at the same time can only be opened one,

CodePudding user response:

COM the old things must use the OPEN time, notification system "occupy" state, CLOSE out, can't two or more devices used at the same time,

CodePudding user response:

Can only be opened by a program, first of all, the COM cannot use other program after open,
Your this requirement, can be realized through the message or otherwise, in A serial interface in the open, after receiving the data synchronization to B form, (news, callback, direct form can be done by reference)

CodePudding user response:

"Read serial data" as A separate control, A/B interface will just call this control to obtain data, this is not conflict