Computer Interfacing
Discussions about interfacing and electronics

RS232 transmits only 16 characters

Transmitting seems to fail due to driver or hardware


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Author Message

May 22, 2011 5:16 pm

I am having troubles transmitting NMEA sentences over the COM port. Receiving sentences works fine, but when transmitting, only 16 characters are send (and received).

At first I didn't know why the instruments that should receive the NMEA sentences were not responding. Then I created a setup with a second computer that would receive the data on a COM port. I used a serial port monitor to view the data. Then I notices just the first 16 bytes were send and the rest of the sentence is never send.

I have a video where you can see that the sentences are sent on the first computer (these are the blue lines). On the second (receiving) computer you can see that the sentences are broken to only 16 chars.

Later I used a external COM port (usb2serial) and the problem did not occur.

Can someone explain the problem and solve it?

ximp dot nl/output_test.mp4

May 23, 2011 9:34 am

This sounds like a handshaking problem. You should try linking the RTS/CTS pins

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