[OT?]When an USB to RS232 converter is not "transparent"? DTR DSR loopback?

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- blisca
  
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posted
16 years ago

Sat, Mar 8, 2008 6:45 AM

I have to solve this ..by phone!,i need your help,or your hints.

There is a little application done in VB that reads and sends data to a board using the MSComm object.It works fine on a Pc with its RS232 serial port. As noticed newest laptops has plenty of USB's but no RS232 ports. So a USB to serial was bought,installed as a COM1 (or COM3 i don't remeber exactly now) with no conflicts at all.

At this point all i know is that the vb program does not works about serial communication.

I would dare to ask wich kind of problem could be caused by a loopback wiring DTR-DSR-CD with this kind of adapters.Why a "real" serial port should work if wired via a pin-to-pin cable,and why a serial-USB adapter should not?

Thanks by Diego Milan,Italy

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- sky465nm
  
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posted
16 years ago

Sat, Mar 8, 2008 6:55 AM

USB "rs232" isn't fully transparent with the real thing. With a processor bus wired rs232 uart you can play with i/o registers directly. And the latency is very low. Neither is true for usb-rs232.

Btw, it's not forbidden to state the full enviroment of the problem.

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