It appears you are trying to build a (relatively standard) null modem cable for RS-232 with male D connectors on both ends.
You have omitted ground, pin 7 of 25-pin connector should go to pin 5 of 9-pin connector.
And the RS-232 connections should be ready.
The other pins like 9&11 you might leave unused if you are not using RS-485.
They or any of the power providing pins on the connector do not connect anywhere if the other communication device is just a PC with 9-pin RS-232.
The RS-485 and power pins are there for connecting to somewhere else than a PC.
Answer from Justme on Stack ExchangeUS Converters
usconverters.com › index.php
RS232 Pinout : U.S. Converters LLC, Serial Data Communication
The primary purpose of the RS232 9-pin pinout is to establish connections between Data Terminal Equipment (DTE) and Data Communication Equipment (DCE), enabling effective data transmission between devices such as computers and modems. A null modem cable enables direct communication between ...
Virtual COM Port Driver
virtual-serial-port.org › virtual serial port driver › articles › what is serial port › rs232 pinout
All you have to learn about serial connector pinouts
October 3, 2024 - They are commonly designated as DB-9 or DB-25 with the number used to differentiate between the pin counts. Various manufacturers’ names may replace the DB in the specifications.
Videos
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RS-232 Explained: Working Principle, Pinout, Cables & Applications ...
What is the RS-232 9-pin pinout?
The RS-232 9-pin pinout refers to the specific signal assignment for each pin on a DB9 connector used in serial communication. Each of the 9 pins carries a distinct signal — including data transmission, handshaking, and ground — that allows two devices to communicate over a serial connection.
stratusengineering.com
stratusengineering.com › home › rs232 9 pin pinout: here’s what you need to know
RS232 9 Pin Pinout: Complete DB9 Pin Diagram & Wiring Guide
What are the three most important pins on an RS-232 connector?
For basic serial communication, only three pins are required: Pin 2 (RXD – Received Data), Pin 3 (TXD – Transmit Data), and Pin 5 (GND – Signal Ground). All other pins support handshaking and flow control, which are optional depending on the application.
stratusengineering.com
stratusengineering.com › home › rs232 9 pin pinout: here’s what you need to know
RS232 9 Pin Pinout: Complete DB9 Pin Diagram & Wiring Guide
How do I monitor or capture RS-232 serial data?
To monitor RS-232 serial data without interrupting the connection, a passive tap device — such as the EZ-Tap or EZ-Tap Pro from Stratus Engineering — can be inserted inline between the DTE and DCE. This allows real-time data capture for debugging, logging, or protocol analysis.
stratusengineering.com
stratusengineering.com › home › rs232 9 pin pinout: here’s what you need to know
RS232 9 Pin Pinout: Complete DB9 Pin Diagram & Wiring Guide
Stratus Engineering
stratusengineering.com › home › rs232 9 pin pinout: here’s what you need to know
RS232 9 Pin Pinout: Complete DB9 Pin Diagram & Wiring Guide
July 20, 2016 - The RS-232 9-pin pinout refers to the specific signal assignment for each pin on a DB9 connector used in serial communication.
Cable Tester
cable-tester.com › home › pin out › rs232 pin out
RS232 Pin Out | Connector Reference Guide - Cable Tester
January 5, 2020 - Pin out diagram of a RS232 pin out with 9 pins d-sub connector (male & female). Also includes references guide to RS232 max cable length.
Decisive Tactics
decisivetactics.com › support › view
DB-9 Connector Pinout - Decisive Tactics, Inc.
Below is the pinout of a typical 9 pin RS-232 connector, this connector type is also referred to as a DB-9 connector.
Leads Direct
leadsdirect.co.uk › technical-library › pinouts-wiring-diagrams › serial-wiring
Leads Direct | Serial Wiring
This port supports a variety of devices, including a serial mouse, serial printer or modem that requires serial data transmission. Possibly the most common serial port is a 9 pin D shape. Connections to these connectors are most commonly made by soldering the cables to the ‘solder bucket’ ...
Extron
extron.com › download › files › userman › RS-232cablecard68-1353-01A.pdf pdf
9-pin D Male to Female RS-232 Cable Guide
functions. UC cables can also be used for contact closure remote · control of specific Extron switchers. Contact closure momentarily · shorts an input's pin on a remote connector to ground.
Details Pin
detailspin.com › home › standard 9 pin serial cable pinout
Ultimate Guide to Standard 9 Pin Serial Cable Pinout - Everything You Need to Know
November 21, 2025 - In the world of connectivity, there ... This component, known as a standard 9 pin serial cable pinout, plays a crucial role in establishing communication between devices that employ serial communication protocols....
Pinout Guide
pinoutguide.com › SerialPortsCables › Nullmodem9to9_pinout.shtml
RS-232 serial cable pinout signals @ PinoutGuide.com
Pinout of Null modem cables and layout of 9 pin D-SUB female connector and 25 pin D-SUB female connectorDE-9 to DE-9, DE-9 to DE-25 cables. Use this cable to connect two devices equipped with serial RS-232 interface. This cable may be used to ...
ShowMeCables
showmecables.com › blog › post › DB9-Connector-Pinout
DB9 Connector Pinout | ShowMeCables.com
June 28, 2023 - A null modem DB9 serial cable (frequently called a crossover cable) is used to connect two Data Terminal Equipment (DTE) devices together without the use of a Data Circuit Equipment (DCE) device in between.
Eltima
eltima.com › eltima software › articles › 9 pin serial cable
What is RS232 DB9 serial port | RS232 pinout
June 22, 2020 - This is a cold boot, after which the RTS line will be set to negative. Setting the RTS line to a positive level is considered a RTS toggle. Here is the layout and function of the 9 pins: Serial data parameters are 1200bps, 7 databits, 1 stop-bit.
F5 Networks
techdocs.f5.com › en-us › hw-platforms › f5-plat-accessories › title-pinouts.html
Cable and Adapter Pinouts | BIG-IP Documentation
Note: These platforms have a 9-pin serial port: BIG-IP 1600/3600/3900/6900/8900/8950/11000/11050. This table lists the pinouts for a RJ45/DE-9 console cable that connects to the RJ45 console port on your platform.
Pinout Guide
pinoutguide.com › SerialPorts › Serial9_pinout.shtml
RS-232 DB9 pinout signals @ PinoutGuide.com
Pinout of PC serial port (RS-232 DE9) and layout of 9 pin D-SUB male connector and 10 pin IDC male connectorThis RS232C DE-9 (usually miscalled DB-9) port is available in some PCs and many other devices.
Campbell Scientific
campbellsci.com › p17855
17855 - Serial Cable, DB9 Pin (Male) to Pigtail
One end of the cable is fitted with a DB9 pin (male) connector. The other end of the cable has stripped and tinned leads. This cable is commonly used to connect the RS-232 port of an AVW200, cellular modem, or other serial DCE device to the ...
Lammert Bies
lammertbies.nl › home › tutorials on computer interfacing › cables for data interfacing › rs232 serial cables pinout
RS232 serial cable pinout information - Lammert Bies
August 18, 2021 - The original pinout for RS232 was developed for a 25 pins sub D connector. Since the introduction of the smaller serial port on the IBM-AT, 9 pins RS232 connectors are commonly used. In mixed applications, a 9 to 25 pins converter can be used to connect connectors of different sizes.
Firewall.cx
firewall.cx › networking › network-cabling › network-serial-cable.html
Serial Direct Cable Connection, DB9, DB25, COM Ports and Pinouts
Because you can have different configurations, e.g. DB-9 to DB-9, DB-9 to DB-25, and DB-25 to DB-25, I have created different tables to show you the pinouts for each one: 1) DB-9 to DB-9. You use this configuration when you need a cable with a DB-9 connector on each end: Figure 6. DB-9 to DB-9 Null Modem (serial) Cable
Juniper Networks
juniper.net › documentation › us › en › hardware › mx2020 › srx4600 › topics › concept › port-rj45-db9-adapter-pinout.html
RJ-45 to DB-9 Serial Port Adapter Pinout Information | Juniper Networks
The console port on a Juniper Networks device is an RS-232 serial interface that uses an RJ-45 connector to connect to a management device such as a laptop or a desktop PC. If your laptop or desktop PC does not have a DB-9 plug connector pin and you want to connect your laptop or desktop PC to the device, use a combination of the RJ-45 to DB-9 socket adapter along with a USB to DB-9 plug adapter. Table 1 provides the pinout information for the RJ-45 to DB-9 serial port adapter.
Plugable
kb.plugable.com › serial-adapter › what-is-the-pinout-of-the-rs-232-connector
What is the pinout of the RS-232 connector? - Plugable Knowledge Base
May 14, 2026 - The RS-232 connector on the PL2303-DB9 uses a standard DTE pinout. The pin numbering can be found inside the DB9 connector of the adapter to identify the
Zebra Support Community
supportcommunity.zebra.com › s › question › 0D56S0000EapiK9SQI › need-9-pin-diagram-for-serial-cable-cbar07s07parcable-rs232-db9-female-connector-7ft-21m-straight-txd-on-2-requires-12v-power-supply
Need 9 Pin Diagram for Serial Cable CBA-R07-S07PAR ...
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