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17 votes

DB9 male or female Connector in Board

The original plan when the D-sub connector family was introduced was that equipment would always have female connectors and cables would always have male connectors. The idea was that pins are easily ...
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7 votes
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Changing DB9 Gender: Crossover or Straight?

The only way to be sure is to measure the voltage on pins 2 and 3 with a multimeter while the device is powered up, but otherwise idle. The pin that is functioning as an output (regardless of whether ...
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6 votes
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3.5mm to DB9 connector (differences)

You have two cables, one works and another does not. What is similarity and what is the difference? Similarity: both are black cables, looking like the same; both are having DB9 (male or female - ...
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6 votes
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PS/2 keyboard with RS232 (DB9) workstation port

That PS/2 to serial adapter is meant only for mice that already have support for both PS/2 and RS232 interfaces built in, so the adapter only needs to connect correct wires to correct pins, so it does ...
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6 votes
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How can I use a serial port to listen to if a toggle is switched?

The basic idea is correct even though the details how you think it works are not entirely correct. Yes, you can connect DTR to DSR via a switch and be able to detect the switch state by reading the ...
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5 votes
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Does this wiring pattern for a DB9 cable exist as a standard cable?

That is a standard null modem cable with handshake also known as crossover. It is used to connect two DCE devices or two DTE ...
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4 votes
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Extra 2 DB9 pins connection

They're the two sets of pins leading downwards on the sides of the connector. Is it connected to chassis ground or is it an NC just to provide more stability for the mechanical and vibration ...
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4 votes
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Capacitors for MAX232

Just use the higher of the recommended values. For example, as per Table 9: Capacitor Value C1 0.1 µF C2, C3, C4 0.33 µF Cbypass 0.33 µF Typically, you'd want the lowest possible capacitance for ...
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4 votes
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How should I mount DB9 Connector?

You could also use a DB9 terminal with an IDC connector, I suppose you use a pitch of 2.54 mm. e.g. 2_54mm-pitch DP9 Connector
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4 votes

Is it common practice to connect power supply to a DB9?

It is common, but only in systems which will never be connected to a serial port. If you do that, you get what you deserve. Probably there is an exception in CANBus systems which are connected to a ...
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4 votes

Is it common practice to connect power supply to a DB9?

D-Subminiature connectors are just that, connectors. They can be used for a variety of purposes besides computer serial ports (although that's probably their most familiar application). Some ...
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3 votes

How should I mount DB9 Connector?

This is the limitation of using generic 0.1" PCBs or breadboards — many components cannot be mounted in them directly. A summary of alternatives, from neatest to worst in my opinion: Get a custom PCB ...
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3 votes

What could be the reason for this RS422 wiring?

Most folk wiring up differential serial interfaces just assume the there are two TX wires and two RX wires and that if it doesn't work with the first attempt then you swap things round and then it ...
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3 votes

How to mount a DB-9 adapter to an enclosure

Those look like they are designed to join two cables together, not in a box or anything, just cable to cable. Look for a bulkhead or panel mount connector or feedthrough. You might also be able to ...
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3 votes

Changing DB9 Gender: Crossover or Straight?

This depends on whether the devices are "DTE" or "DCE". If they're both computers, you need a null modem. If one of them is a modem, or modem-like device, then you don't.
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3 votes
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What is a 3 wire type cross linked serial cable?

Yes - I would call that a Null Modem cable. If the cable you get (or make) doesn't work, my first debugging step for serial communications is to swap connections on pins 2 and 3. (Transmit and ...
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3 votes

Can I connect a "J1708" port to my computer?

Warning: J1708 is not the same as RS-485! The only time you can use an RS485 port on the J1708 bus is if you NEVER transmit. The receiver is compatible but the transmitter is not. So if you just ...
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2 votes

What is a 3 wire type cross linked serial cable?

Whether it is a null-modem cable depends on your definition. Yours can be described as a partial null-modem cable, in that it does not incorporate hardware flow control. Or, since most PCs these days ...
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2 votes

What is a 3 wire type cross linked serial cable?

Since the TXD (3) of one side is connected with the RXD (2) of the other, this is indeed a null-modem cable. Normal serial cables have pins 2 and 3 connected straight through, and the DCE is ...
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2 votes
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Making a DB9 Cable

As an alternative I recommend screw-type connectors. They are easy to wire for one-off jobs, can be rewired if you make a mistake and easy to inspect. Note that they are more bulky than soldered ...
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2 votes

Db9 shield connection? in plastic hood!

Although RS-485 is a robust interface, it can be brought to its knees with common-mode problems. Physical distance between nodes and not having a really solid ground that ties all the nodes together ...
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2 votes
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DB9 male or female Connector in Board

Use Db9 female connector in your board, since PC have DB9 male connector , or if your PC dont have DB9 then you may need to used RS232 to USB converter cable, which has male DB9 port.
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2 votes
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How to Make DB9 F/F serial RS232 mini gender changer?

Thank you Finbarr and JRE. The Connection i was looking for was found in the manual of instrument: Outcome:
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2 votes

How to Make DB9 F/F serial RS232 mini gender changer?

If all you need is a pure gender changer, I wouldn't bother making one because they're easy enough to buy: Just search for DB9F Gender Changer or something similar. You could make one yourself by ...
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2 votes
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Serial DB9 to Serial 3.5mm over HDMI cabling

Using an HDMI cable for rs232 isn't a problem. A cable is a cable is a cable. As long as you are sure it won't be plugged into an HDMI device by mistake (typically not a problem in one off hobby ...
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2 votes

Two devices on Y 9pin Serial cable to 25pin printer input - Data Corruption

Any insight as to why the other unit wouldn't print when both devices are attached? Yes. An idle device will try to drive the Tx line to some negative voltage (anywhere from -3V to -15V), while the ...
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2 votes

3.5mm to DB9 connector (differences)

A 3.5mm jack isn't a standard connector for serial links. The chances are the device manufacturer used one because it was all that would fit in their device. As a result, there's no standard for how ...
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  • 15k
2 votes

Is it common practice to connect power supply to a DB9?

There is an industry standard DB9 pinout for CAN which is set by CANopen DS303.1 6.1: This is a widely accepted standard. Anyone deviating from this pin-out for CAN applications is making non-...
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