Cable Pinouts

RS232

RS232 standards are defined by EIA/TIA (Electronic Industries Alliance /Telecommunica- tions Industry Association). RS232 defines both the physical and electrical characteristics of the interface. RS232 is practically identical to ITU V.24 and V.28 (electrical). RS232 is an Active LOW voltage driven interface and operates at +12V to -12V where:

Signal = 0 (LOW) > +3.0V

Signal = 1 (HIGH) < -3.0V

Signal voltages in the range >-3.0V to +3.0V is regarded as the 'dead area' and allows for absorption of noise.

Please watch carefully the terms DTE (Data Terminal Equipment - e.g. a terminal or PC) and DCE (Data communications Equipment - e.g. a modem) the meaning and use of certain pins may differ. The diagrams below define the interface from the DTE perspec- tive. The NPC-1 has a RS232 DTE connection.

RS232 on DB9 (EIA/TIA 574)

Pin No. Description

1DCD, Data Carrier Detect

2RxD, Receive Data

3TxD, Transmit Data

4DTR, Data Terminal Ready

5GND, Ground

6DSR, Data Set Ready

7RTS, Request To Send

8CTS, Clear To Send

9RI, Ring Indicator

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