> 3.11 | Serial Interface ASC1

> The ASC1 interface is available as a 4-wire unbalanced, asynchronous modem interface ASC1 conforming to ITU-T V.24 protocol DCE signalling. The electrical characteristics do not comply with ITU-T V.28. The significant levels are 0V (for low data bit or active state) and 2.9V (for high data bit or inactive state). For electrical characteristics please refer to Table 30.
> TC65 is designed for use as a DCE. Based on the conventions for DCE-DTE connections it communicates with the customer application (DTE) using the following signals:

> • | Port TXD @ application sends data to module’s TXD1 signal line

> • | Port RXD @ application receives data from the module’s RXD1 signal line

> Figure 18: Serial interface ASC1
> Features

> • | Includes only the data lines TXD1 and RXD1 plus RTS1 and CTS1 for hardware handshake.

> • | On ASC1 no RING line is available. The indication of URCs on the second interface depends on the settings made with the AT^SCFG command. For details refer to [1].

> • | Configured for 8 data bits, no parity and 1 or 2 stop bits.

> • | ASC1 can be operated at fixed bit rates from 300 bps to 460,800 bps. Autobauding is not supported on ASC1.

> • | Supports RTS1/CTS1 hardware flow control and XON/XOFF software flow control.

> Table 16: | DCE-DTE wiring of ASC1

> V.24 circuit | DCE | DTE
> Pin function | Signal direction | Pin function | Signal direction
> 103 | TXD1 | Input | TXD | Output
> 104 | RXD1 | Output | RXD | Input
> 105 | RTS1 | Input | RTS | Output
> 106 | CTS1 | Output | CTS | Input