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WA_DEV_FEX20_UGD_002 Rev 002 April 26, 2010 40
Fastrack Xtend User Guide Interfaces
Figure 9. RS232 Serial Link Signals
The RS232 interface has been designed to allow flexibility in the use of the serial interface signals.
However, the use of TXD, RXD, CTS and RTS signals are mandatory; while the use of DTR, DSR,
DCD and RI signals are optional.
Tip: The Fastrack Xtend is designed to operate using all serial interface signals and it is recommended to
use CT105/RTS and CT106/CTS for hardware flow control in order to avoid data corruption during
transmission.
The Fastrack Xtend also implements the Serial Port Auto Shut Down feature with the DTR signal. It is
recommended to use the CT108-2/DTR signal to benefit from the current consumption improvement
performed by this feature.
5.1.2.1.1. RS232 Implementation
The following subsections describe how the RS232 serial link can be implemented to suit different
designs.
5.1.2.1.1.1. 5-wire Serial Interface RS232 Implementation
The signals used in this interface are as follows:

CT103/TXD

CT104/RXD

CT105/RTS

CT106/CTS

CT108-2/DTR
Note: The CT108-2/DTR signal must be managed following the V24 protocol signaling if the Sleep Idle
Mode and Serial Port Auto Shut Down feature are to be used.