Cinterion
®
EMS31-US Hardware Interface Overview
2.1 Application Interface
17
EMS31_US_HIO_v00.103
2017-11-27
Confidential / Preliminary
Page 10 of 33
2.1.2
Serial Interface ASC1
EMS31-US provides a 4-wire unbalanced, asynchronous modem interface ASC1 conforming
to ITU-T V.24 protocol DCE signaling. 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 inactive state).
EMS31-US 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 3:
Serial interface ASC1
Features
•
Includes only the data lines TXD1 and RXD1 plus RTS1 and CTS1 for hardware hand-
shake.
•
On ASC1 no RING line is available.
•
Configured for 8 data bits, no parity and 1 or 2 stop bits.
•
ASC1 can be operated at fixed bit rates from 1,200 bps to 3,686,400bps.
•
Supports RTS1/CTS1 hardware flow control. Communication is possible by using only RXD
and TXD lines, if RTS1 is pulled low.
TXD1
RXD1
RTS1
CTS1
TXD
RXD
RTS
CTS
Module (DCE)
Application (DCE)
