Connectors are not part of RS-485 standard.
As the old joke has it, standards are so good everyone should have their own:
Here are several conflicting specifications for half-duplex RS-485 on D-shell 9-pin connectors:
- Modbus uses pins 5 and 9 and 1. Standard, section 3.5
- Digi uses 3 and 9 and 5. Ref
- Virtual Serial Port uses 3 and 7 and shell. Ref, fig 3.9
If there's something common in your industry, use that. Otherwise I'd suggest Modbus, because "RS-485 on DE-9 per Modbus standard" is easy to say, easy to check, and buy ready-made cables for.
Answer from jonathanjo on Stack Exchange Top answer 1 of 3
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Connectors are not part of RS-485 standard.
As the old joke has it, standards are so good everyone should have their own:
Here are several conflicting specifications for half-duplex RS-485 on D-shell 9-pin connectors:
- Modbus uses pins 5 and 9 and 1. Standard, section 3.5
- Digi uses 3 and 9 and 5. Ref
- Virtual Serial Port uses 3 and 7 and shell. Ref, fig 3.9
If there's something common in your industry, use that. Otherwise I'd suggest Modbus, because "RS-485 on DE-9 per Modbus standard" is easy to say, easy to check, and buy ready-made cables for.
2 of 3
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No, because the RS-485 standard itself does not define any connector or any pinout, among many other things that the standard does not define.
Also a DB9 connector does not exist, but I will assume you mean DE9 connector.
However, many other standards that build on top of the RS-485 standard do define a connector and a pinout. So this means there can be many different pinouts used by many different standards on DE9 connector.
Just pick a pinout that is commonly used, standard or non-standard.
Many other differential buses that don't use RS-485 but still have rather compatible cabling and might use a DE9 connector in practice do exist.
Brainboxes
brainboxes.com › home › pinouts - how do i wire my brainboxes db9 serial port for rs485 half-duplex ?
How do I wire my Brainboxes DB9 serial port for RS485 Half-Duplex ? | Brainboxes Documentation
1 week ago - Quite often, RS-485 Half-Duplex capable devices feature a 3-Pin connector, with the following pin assignments: Data+, Data- & GND (Ground). The following 3 diagrams (Figure 2 – 4) will illustrate connecting an equivalent 3-Pin connector in ...
RS232 and RS485 DB9 pinouts
Hi guys. In my current project i am trying to communicate with RS232 and RS485. Both should be present but one should be active. I am using MAX3160E transceiver, which allows me to switch between RS232 and RS485. Aim is to connect them to DB9 and control the transceiver to switch. But pin... More on forum.allaboutcircuits.com
3
February 28, 2022RS485 DB9 standard connection
I have never come across a RS485 'standard' socket, but the DB9 was used to replace the 25pin DB25 socket for RS232 COM port. Max. ... Google is your friend! https://opengear.zendesk.com/hc/en-...S232-RS422-RS485-standard-DB-connector-pinout More on forum.allaboutcircuits.com
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October 3, 2024Standard connector/pinout for RS-485?
Standard: two screw terminals labeled + and -. See www.Modbus.org The problem with your idea is that often RS-485 requires termination resistors to prevent communication problems from reflections. So with screw terminals we can just insert the resistor. If anything make it plug-in. That way it is a “plug” but one I can easily wire up. With DB-9, RS-485, etc., we can’t do any of that. We are back to making goofy connectors by hand. The pins require special tools and often fall out. DB9 was used because DB25 was huge. DB25 existed for mouse immunity with every other pin grounded back in the teletype days with massive noise problems if the day. Connections were still soldered so a hollow pin made lots of sense at that time. Plus DB9 is already associated with RS-232. RJ-45 is Ethernet. Reusing these (which some vendors do) just creates confusion. If I see DB9, there’s a 95% chance it’s RS-232. There are vendors who do this (Allen Bradley) and it causes nothing but problems. People are constantly trying to plug an Ethernet device into the RS-485 “DPI” ports. Now there are exceptions and this is also why AB and others do it. A common configuration is where you have say an RJ-45 or RJ-11 or RJ-12 6P6C connector bug two pins carry 24 V and ground abc 2 carry RS-485/Modbus. This is a “remote keypad” port used on a lot of VFDs on the market. It has the convenience that the port can double as a programming or networking port and that if the factory cable breaks you can get a new one anywhere. More on reddit.com
11
2
July 26, 2022USB rs-485 pinouts
I can't seem to get the USB to RS-485 Cable to work with Modbus RTU communication. My system works with third party USB-rs485 converters but not with the NI cable. I have installed the driver properly, and the communication settings are correct. On the DB9 connector I have Ground on pin 1, Data... More on forums.ni.com
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January 16, 2012Videos
00:16
DB9 Pinout Confusion Solved #RS485 #automation - YouTube
00:47
Brainboxes - RS-422 485 DB9 Connector Pinouts - YouTube
09:28
RS-232 vs RS-485 Control Cabling (DB9 and RS-422 Explained) - YouTube
08:27
RS232 DB9 Termination + Testing - Step-by-Step Guide - YouTube
Virtual COM Port Driver
virtual-serial-port.org › serial port software › articles › what is serial port › rs485 pinout
RS485 Pinout - RS485 connector pinout and contacts
October 3, 2024 - There is no specific type of connector used to implement the RS485 protocol but in most scenarios, a DB9 connector or terminal block are employed. Specific RS485 connectors may have different pinouts.
Alicat
documents.alicat.com › pinouts › DOC-PINOUT-DB9.pdf pdf
DOC-PINOUT-DB9 - REV 12, November 2023 3 ⁄ 40 TM +1 (888) 290-6060
DB9 (Male and Female) Standard Pinout · Always identify proper wiring via continuity check & color when using multi-strand cables. The calibration certificate for the device should be used as the definitive reference for custom wiring options. Note: Do not connect RS-485 to RS-232 units or cables.
All About Circuits
forum.allaboutcircuits.com › home › forums › hardware design › digital design
RS232 and RS485 DB9 pinouts | All About Circuits
February 28, 2022 - God the days of having to carry ... you can just use 3 pins, RX,TX and GND with the handshake jumpered out. IIRC it is 6-7 and 8-1-4 on the DB9....
All About Circuits
forum.allaboutcircuits.com › home › forums › hardware design › general electronics chat
RS485 DB9 standard connection | All About Circuits
October 3, 2024 - Google is your friend! https://opengear.zendesk.com/hc/en-...S232-RS422-RS485-standard-DB-connector-pinout · Click to expand... This is one way doing it, don't think it's universally accepted standard, however. ... I have never come across a RS485 'standard' socket, but the DB9 was used to replace the 25pin DB25 socket for RS232 COM port.
Reddit
reddit.com › r/plc › standard connector/pinout for rs-485?
r/PLC on Reddit: Standard connector/pinout for RS-485?
July 26, 2022 -
I'm developing some automation equipment that will go into an overseas factory. The factory would like to communicate with the equipment and I'm recommending to do so via RS485; however, I can't seem to find any standard or best-practice connectors and/or pinouts. Seems like DB9 or RJ45 would be good options, but searching online shows a variety of pinouts. I'd imagine that you'd need adapters for different pieces of equipment from different manufacturers to talk to each other. Is that they way it is, or am I overlooking a standard? Thanks!
Top answer 1 of 6
4
Standard: two screw terminals labeled + and -. See www.Modbus.org The problem with your idea is that often RS-485 requires termination resistors to prevent communication problems from reflections. So with screw terminals we can just insert the resistor. If anything make it plug-in. That way it is a “plug” but one I can easily wire up. With DB-9, RS-485, etc., we can’t do any of that. We are back to making goofy connectors by hand. The pins require special tools and often fall out. DB9 was used because DB25 was huge. DB25 existed for mouse immunity with every other pin grounded back in the teletype days with massive noise problems if the day. Connections were still soldered so a hollow pin made lots of sense at that time. Plus DB9 is already associated with RS-232. RJ-45 is Ethernet. Reusing these (which some vendors do) just creates confusion. If I see DB9, there’s a 95% chance it’s RS-232. There are vendors who do this (Allen Bradley) and it causes nothing but problems. People are constantly trying to plug an Ethernet device into the RS-485 “DPI” ports. Now there are exceptions and this is also why AB and others do it. A common configuration is where you have say an RJ-45 or RJ-11 or RJ-12 6P6C connector bug two pins carry 24 V and ground abc 2 carry RS-485/Modbus. This is a “remote keypad” port used on a lot of VFDs on the market. It has the convenience that the port can double as a programming or networking port and that if the factory cable breaks you can get a new one anywhere.
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There’s no standard, except for everyone’s standard.
shadeBlue Help Desk
support.shadeblue.com › hc › en-us › articles › 114094174832-RS232-RS422-RS485-DB9-DB25-serial-port-pinouts-and-loopback-wiring
RS232 / RS422 / RS485 DB9 & DB25 serial port pinouts and loopback wiring – shadeBlue Help Desk
October 27, 2016 - This connector is found on National Instrument’s one and two port serial interfaces. ... To perform a loopback test with no hardware flow control, you will need to connect pins 2 and 3 for RS-232 and pins 4 to 8 and 5 to 9 for RS-422/485.
AliExpress
aliexpress.com › s › wiki-ssr › article › 485-db9-pinout
Everything You Need to Know About the 485 DB9 Pinout for Reliable Industrial Communication
The article explains the recommended RS485 DB9 pinout using pins 3 2 and 5 for reliable industrial communications, emphasizing proper wiring avoids signal loss and ensures accurate differential signaling.
Digi
docs.digi.com › resources › documentation › digidocs › 90001537 › references › r_rs_485_db9_on_connect.htm
RS485 DB9 on Connect Products
This Wiki page directly covers products which use a standard DB9 serial port (a DTE or PC-like port).
RF Wireless World
rfwireless-world.com › terminology › rs485-pin-diagram-db9-connector
RS485 Pin Diagram and Specifications for DB9 Connector | RF Wireless World
The following describes the RS485 pin diagram for a 9-pin connector. Tx+ and Tx- carry transmit data, and Rx+ and Rx- carry receive data.
DFRobot
dfrobot.com › home › prototyping & accessories › electronics › headers › db9 male connector for rs232/rs422/rs485
DB9 Male Connector For RS232/RS422/RS485 - DFRobot
DB9 Male Connector For RS232/RS422/RS485
A high-quality DB9 Male Connector for RS232, RS485, RS422 interfaces. Maximum RS232 cable length varies with baud rate. Includes one connector.
Price $0.39
NI Community
forums.ni.com › community › discussion forums › most active software boards › labview › usb rs-485 pinouts
Solved: USB rs-485 pinouts - NI Community
January 16, 2012 - Does the RS485 device that you are trying to communicate with use the 2-wire mode or 4-wire mode? The NI USB-485 converter comes wired for the 4-wire mode. To use it in the 2-wire mode simply install a jumper between pins 4-8 (+) and 5-9 (-) on your DB9. Connect (+), (-), and ground (pin-1) ...
openHAB Community
community.openhab.org › setup, configuration and use › beginners
Modbus over RS485 (RJ45 to DB9) cable lenghth and pinout - Beginners - openHAB Community
June 6, 2023 - Hi All I am about to take delivery of my SunSynk inverter which does not seem to have any binding support (using the new SunSynk logger). So it appears that I will have to revert to MODBUS over RS485, so I have a few q…
Opengear
portal.opengear.com › s › article › RS232RS422RS485standardDBconnectorpinout661d308e7cf0c
RS232, RS422 & RS485 standard DB connector pinout - Opengear
Opengear - RS232, RS422 & RS485 standard DB connector pinout RS232, RS422 & RS485 standard DB connector pinout RS232 pinout RS232 pinout standards exist for both DB9 and DB25 connectors as shown below: DB25SIGNALDB9DEFINITION1 Protective Ground2TXD3Transmitted Data3RXD2Received Data4RTS7Request To Send5CTS8Clear To Send6DSR6Data Set Ready7GND5Signal Ground8CD1Received Line Signal Detector9 Reserved for data set testing10 Reserved for data set testing11 Unassigned12SCF Secndry Rcvd Line Signl Detctr13SCB Secondary Clear to Send14SBA Secondary Transmitted Data15DB Transmisn Signal Timng16SBB Sec
Etechnophiles
etechnophiles.com › what-is-rs485-advantages-pinout
What is RS485 Pinout, 12 Key Advantages & FAQs
March 21, 2024 - RS485 is a popular standard in serial data communication. It has several advantages and hence it is applied on numerous platforms for effective data transfer. The pinout of RS485 shows that it has a 9-pin DB9 connector.
Reddit
reddit.com › r/plc › does a cable with de-9 connector on both ends work for both rs485 and rs232 interfaces
r/PLC on Reddit: Does a cable with DE-9 connector on both ends work for both RS485 and RS232 interfaces
October 10, 2023 -
Because a DB9 cable on startech is claimed to be RS232.
https://www.startech.com/en-eu/cables/mxt1001mbk
Top answer 1 of 4
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For 485 I think you need a resistor at both ends.
2 of 4
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Most likely, no. Even RS-232 had numerous implementations, with control lines jumpered, or not, and straight through or null modem. 485 has, in comparison few, if any DB9 implementations, and those tend to be screw terminal. Even 485 is RJ-45, the pinouts differ from vendor to vendor.
Acesinc
acesinc.com › wp-content › uploads › 2015 › 06 › DB9_connector_wiring.pdf pdf
DB9 Connector Wiring DB9 Cable Pinout Controller Connections RS-232 RS-485
DB9 Connector Wiring · DB9 Cable Pinout · Controller Connections · RS-232 · RS-485 · Signal · 96 Controller · F4 Controller · (RS-232) F4 Controller · (RS-485) Pin 5 · Pin 5 · Common · 20 · 16 · 16 · Pin 3 · Pin 2 · Receive · 21 · 15 · 12 · Pin 2 ·