B&B Electronics ESU2-400 - Manual - Manual (Page 16)

Making external connections USB-to-Serial Adapter User’s Manual
Page 12 Rev 1.01 (February 2007)
Making external connections
The USB-to-Serial adapters are equipped with male DB-9 connectors.
The following figures and tables show the serial port pinouts for RS-
232 and RS-232/422/485 applications.
Figure 12 - DB-9 connector pinout
RS-232 serial connections
RS-232 devices are classified by their function as either Data
Terminal Equipment (DTE) or Data Communication Equipment
(DCE).
Figure 13 - Use of DTEs and DCEs in a communication link
The USB-to-Serial adapters are DTE devices that connect to
peripheral equipment through a male DB-9 connector. The following
table lists the serial port connector definitions.
Table 4 - RS-232 signals on DB-9 connector
RS-232 signal description DB-9
Data Carrier Detect (DCD) 1
Receive Data (RxD) 2
Transmit Data (TxD) 3
Data Terminal Ready (DTR) 4
Signal Ground (GND) 5
Data Set Ready (DSR) 6
Request To Send (RTS) 7
Clear To Send (CTS) 8
Ring Indicator (RI) 9
Note: A DTE device is the
communication source. A DCE
device provides a communication
channel between two DTE-type
devices.