# Serial Channel: End of transmission

**URL:** <https://forums.digi.com/t/serial-channel-end-of-transmission/4520>\
**Category:** NET+OS\
**Created:** [February 20, 2004, 1:11pm UTC](https://forums.digi.com/t/serial-channel-end-of-transmission/4520 "2004-02-20T13:11:52Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![system](https://us1.discourse-cdn.com/flex016/uploads/digi/original/1X/11da31a6a1fbcd03ef21d3f785c317c824009ae2.png) [@system](https://forums.digi.com/u/system)\
**Post date:** [February 20, 2004, 1:11pm UTC](https://forums.digi.com/t/serial-channel-end-of-transmission/4520/1 "2004-02-20T13:11:52Z")

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Because of the not working TXBC I’m trying to recognize the end of a transmission by receiving the data stream I’m transmitting. On my hardware the serial interface is connected to a RS485 driver and when you enable the receiver while you are transmitting (both directions are enabled), you have the same data stream on TXD and RXD. On the NET+50 I enabled the Receive Register Ready Interrupt and the Receive Buffer Closed Interrupt. But as my stream of characters (6-18 bytes adjoining each other) is not (often) divisible by 4 without remainder I always lose the last 1-3 characters. As described in this forum I tried to solve the problem by using the Receive Character Gap Timer but this caused even more problems. The Character Gap Timer Interrupt appeared before the gap appeared and so I even lost more characters. Does anybody know, if the problem is caused by the simultaneously transmission and reception or is there another not published field which does not working correctly?