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Chapter 6 Communication Interface
6.1
RS232 Interface
6.1.1
Description
At present, the widely used serial communication standard is the RS-232 standard, it can also be called the
asynchronous serial communication standard, it is used to implement data communication between computers
and computers, between computers and peripherals. RS is the English abbreviation of “Recommended
Standard” 232 is the standard number. This standard is officially published by the Electronic Industries
Association (EIA) in 1969, it specifies that one bit of data is transmitted over a single data line at a time. Most
serial port configurations are usually not strictly based on the RS-232 standard; Use 25-pin connector on each
port (IMB AT uses 9-pin connector). The most common RS-232 signals are shown in the table below.
Table 6-1 RS-232 Signal Table
Like most serial ports in the world, the serial interface of this tester is not strictly based on the RS-232 standard,
but only provides a minimal subset. As shown in the following table:
Signal
Symbol
Connector Pin#
Transmit Data
TXD
3
Receive Data
RXD
2
Grounding
GND
5
Table 6-2 RS-232 Signal Subset Table
This is the easiest and the most cost effective way to use serial ports communication. The RS232C connector of
this tester uses a 9-core pin type DB socket, and the pin sequence is shown in figure 6-1 below:
Signal
Symbol
25-core connector pin
#
9-core connector pin#
Request to Send
RTS
4
7
Clear to Send
CTS
5
8
Data Set Ready
DSR
6
6
Data Carrier Detect
DCD
8
1
Data Terminal Ready
DTR
20
4
Transmit Data
TXD
2
3
Receive Data
RXD
3
2
Grounding
GND
7
5
Содержание TH7105
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