Gemalto M2M GmbH PXS8 Manuel D’Utilisation

3.4 Serial Interface ASC0

PXS8_HD_v03.000

Page 24 of 41

2012-11-30

Confidential / Preliminary

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PXS8 offers an 8-wire unbalanced, asynchronous modem interface ASC0 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 1.8V (for high data bit or in-
active state). 

PXS8 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 the module’s TXD0 signal line

•

Port RXD @ application receives data from the module’s RXD0 signal line

Figure 4:  Serial interface ASC0

Features:
•

Includes the data lines TXD0 and RXD0, the status lines RTS0 and CTS0 and, in addition,
the modem control lines DTR0, DSR0, DCD0 and RING0.

•

ASC0 is designed for controlling GSM/UMTS/CDMA voice calls, transferring data and for
controlling the module with AT commands.

•

Full multiplexing capability allows the interface to be partitioned into virtual channels.

•

The RING0 signal serves to indicate incoming calls and other types of URCs (Unsolicited
Result Code). It can also be used to send pulses to the host application, for example to
wake up the application from power saving state. See 

 for details on how to configure the

RING0 line by AT^SCFG.

•

Configured for 8 data bits, no parity and 1 stop bit. 

•

ASC0 can be operated at fixed bit rates from 9600bps up to 921600bps.

•

Supports RTS0/CTS0 hardware flow control.

•

Wake up from SLEEP mode by RTS0 activation (high to low transition). 

Note. If the ASC0 serial interface is the application’s only interface, it is suggested to connect 
test points on the USB signal lines as a potential tracing possibility.