> 1.6 | Communication between Customer Application and TC65

> Leaving hardware flow control unconsidered the Customer Application (TE) is coupled with the TC65 (ME) via a receive and a transmit line.
> Since both lines are driven by independent devices collisions may (and will) happen. For example, if the TE issues an AT command the TC65 starts sending a URC. This will probably cause the TE to misinterpret of the URC being part of the AT command's response.
> To avoid this conflict the following measures must be taken:

> • | If an AT command is finished (with "OK" or "ERROR") the TE shall always wait at least 100 milliseconds before sending the next one. This gives the TC65 the opportunity to transmit pending URCs and get necessary service. Note that some AT commands may require more delay after "OK" or "ERROR" response, refer to the following command specifications for details.

> • | The TE shall communicate with the TC65 using activated echo (ATE1), i.e. the TC65 echoes characters received from the TE. Hence, when the TE receives the echo of the first character "A" of the AT command just sent by itself it has control both over the receive and the transmit paths.