User guide

WM_PRJ_M12_UGD_001 - 002
18th September 2003
confidential ©
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2.2 RS232 serial link
2.2.1 General presentation
The RS232 interface performs the voltage level adaptation (V24/CMOS
⇔
V24/V28) between the internal WISMO module (DCE) and the external world
(DTE).
The RS232 interface is protected (by ESD protection) against electrostatic
surges on the RS232 lines.
Filtering guarantees:

EMI/RFI protection in input and output,

Signal smoothing.
A flexible 6-wire serial interface is available complying with RS232 protocol
signaling.
The signals available are:
•
TX data (CT103/TX),
•
RX data (CT104/RX),
•
Request To Send (CT105/RTS),
•
Clear To Send (CT106/CTS),
•
Data Terminal Ready (CT108-2/DTR),
•
Data Set Ready (CT107/DSR).
The 2 additional signals are Data Carrier Detect (CT109/DCD) and Ring
Indicator (CT125/RI).
FASTRACK
MODEM
M1206
(DCE)
DTE
CT103 / TX
CT108-2 / DTR
CT105 / RTS
CT104 / RX
CT106 / CTS
CT107 / DSR
CT109 / DCD
CT125 / RI
Figure 7: RS232 Serial Link signals
RS232 interface has been designed to allow a certain flexibility in the use of
the serial interface signals. However, the use of TX, RX, CTS and RTS signals is
mandatory which is not the case for DTR, DSR, DCD and RI signals which can
be not used.