RS422 cable 25 pin to 9 pin - PLCS.net

Steve_D · October 10th, 2002, 08:54 PM

I have a need to connect an RS232 cable to an RS422 port. I have a converter which is 25 pin in and out, I need to connect to 9pin plugs, I have the pin outs for the RS232 cable but don't have the pinouts for a 25 to 9 pin RS422 cable. Can anyone assist. I am assuming that all RS422 plugs are the same pin configuration.

Eric Nelson · October 10th, 2002, 09:33 PM

Assuming you need the 25 to 9-pin adapter on the RS-232 side (to connect to your PC), you can use a standard 25 to 9-pin (male to female) adapter readily available at any computer store. Look in your "junk box", you probably already have one.

For reference, see THIS listing in The Hardware Book

beerchug

-Eric

Eric Nelson · October 10th, 2002, 09:46 PM

Whoops! After re-reading your post, I realized that you need an adapter for the RS-422 side. I don't think these follow any "standard", though I've been wrong before (more than I'll admit!). If there IS a standard, THIS LINK might be helpful for the device side

You'll need to know the pinout of your converter (printed on side maybe?) as well as the pinout of the RS-422 device. What are you trying to connect to? You might find pinouts available from the manufacturer. Once you have that info it's easy.

RX+ to TX+
RX- to TX-
TX+ to RX+
TX- to RX-

Without that info, you're out of luck...

beerchug

-Eric

Steve_D · October 11th, 2002, 07:29 AM

Thanks for the input Eric, I was hoping that wouldn't be the case as I don't have the pinouts for the Converter. I was hoping that all 25 pin RS422 pinouts would be the same otherwise, why sell a converter when the chances are the signals will not be on the pins you want??

Jay Anthony · October 11th, 2002, 07:41 AM

OK. Let us in on it. What are you trying to connect RS422 to? What manufacturer? There's probably one of us that can help you out.

rsdoran · October 11th, 2002, 01:11 PM

I didnt know that a RS422 device wouldn't follow the EIA standards that are set just like RS 232 is.

Two channel adapter port powered
25 Pin Female

1 GND
2 TD (A)
3 RD (A)
5 RD (A)
14 TD (B)
17 RD (B)
18 RD (B)
7 GND

25 +12volt
12 GND

NOTE that just like an RS 232 cable that 2 & 3 are being used to transmit and recieve. EIA RS 422 wasnt designed to change or be different than RS 232, it just allowed longer lengths. Follow the RS 232 pinouts and you should be fine

Jim Dungar · October 11th, 2002, 07:58 PM

EIA does not define which RS232, RS422, or RS485 pin is which function. However there are normal conventions (especially in the computer market), but you always need to know what devices you are connecting to. For example a 25pin device is different than a 9pin, and some DTE connections are opposite from DCE ones.

Right now I have three different RS485 items on my desk and each one has a different pin out as well as different terminology (Tx(B) vs Tx(+)).

Convertors typically use PC conventions, but they are frequently used with custom built cables when connecting to non-computer ports.

rsdoran · October 11th, 2002, 09:04 PM

I disagree but the EIA standards arent free, so I wont argue the point.

The difference is when connecting to DTE or DCE devices, nothing else

Steve_D · October 13th, 2002, 11:33 PM

After much investigation and with the help of your advice I have established communications...thanks for your time guys.

zonix · September 7th, 2003, 11:27 AM

Check this site for RS422 Video information

http://www.rs422.com.ar/#Connect_RS422

October 10th, 2002, 08:54 PM	#1
Steve_D Member Join Date: Jul 2002 Location: Albury/Wodonga Posts: 77	RS422 cable 25 pin to 9 pin I have a need to connect an RS232 cable to an RS422 port. I have a converter which is 25 pin in and out, I need to connect to 9pin plugs, I have the pin outs for the RS232 cable but don't have the pinouts for a 25 to 9 pin RS422 cable. Can anyone assist. I am assuming that all RS422 plugs are the same pin configuration.

October 10th, 2002, 09:46 PM	#3
Eric Nelson Lifetime Supporting Member + Moderator Join Date: Apr 2002 Location: Randolph, NJ Posts: 4,074	Note to self... Always read posts thoroughly before replying... Whoops! After re-reading your post, I realized that you need an adapter for the RS-422 side. I don't think these follow any "standard", though I've been wrong before (more than I'll admit!). If there IS a standard, THIS LINK might be helpful for the device side You'll need to know the pinout of your converter (printed on side maybe?) as well as the pinout of the RS-422 device. What are you trying to connect to? You might find pinouts available from the manufacturer. Once you have that info it's easy. RX+ to TX+ RX- to TX- TX+ to RX+ TX- to RX- Without that info, you're out of luck... beerchug -Eric

October 11th, 2002, 07:29 AM	#4
Steve_D Member Join Date: Jul 2002 Location: Albury/Wodonga Posts: 77	Thanks Eric Thanks for the input Eric, I was hoping that wouldn't be the case as I don't have the pinouts for the Converter. I was hoping that all 25 pin RS422 pinouts would be the same otherwise, why sell a converter when the chances are the signals will not be on the pins you want??

October 11th, 2002, 01:11 PM	#6
rsdoran Lifetime Supporting Member Join Date: Apr 2002 Location: Birmingham, AL Posts: 7,372	I didnt know that a RS422 device wouldn't follow the EIA standards that are set just like RS 232 is. Two channel adapter port powered 25 Pin Female 1 GND 2 TD (A) 3 RD (A) 5 RD (A) 14 TD (B) 17 RD (B) 18 RD (B) 7 GND 25 +12volt 12 GND NOTE that just like an RS 232 cable that 2 & 3 are being used to transmit and recieve. EIA RS 422 wasnt designed to change or be different than RS 232, it just allowed longer lengths. Follow the RS 232 pinouts and you should be fine __________________ http://www.patchn.com Industrial Electrical & Maintenance @ www.patchn.com "Tell me and I forget, show me and I remember, involve me and I understand."

October 11th, 2002, 09:04 PM	#8
rsdoran Lifetime Supporting Member Join Date: Apr 2002 Location: Birmingham, AL Posts: 7,372	I disagree but the EIA standards arent free, so I wont argue the point. The difference is when connecting to DTE or DCE devices, nothing else __________________ http://www.patchn.com Industrial Electrical & Maintenance @ www.patchn.com "Tell me and I forget, show me and I remember, involve me and I understand."



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October 10th, 2002, 09:33 PM	#2
Eric Nelson Lifetime Supporting Member + Moderator Join Date: Apr 2002 Location: Randolph, NJ Posts: 4,074	Assuming you need the 25 to 9-pin adapter on the RS-232 side (to connect to your PC), you can use a standard 25 to 9-pin (male to female) adapter readily available at any computer store. Look in your "junk box", you probably already have one. For reference, see THIS listing in The Hardware Book beerchug -Eric

October 11th, 2002, 07:41 AM	#5
Jay Anthony Member Join Date: Apr 2002 Location: Dallas, TX Posts: 645	OK. Let us in on it. What are you trying to connect RS422 to? What manufacturer? There's probably one of us that can help you out.

October 11th, 2002, 07:58 PM	#7
Jim Dungar Member Join Date: Apr 2002 Location: WI Posts: 1,152	EIA does not define which RS232, RS422, or RS485 pin is which function. However there are normal conventions (especially in the computer market), but you always need to know what devices you are connecting to. For example a 25pin device is different than a 9pin, and some DTE connections are opposite from DCE ones. Right now I have three different RS485 items on my desk and each one has a different pin out as well as different terminology (Tx(B) vs Tx(+)). Convertors typically use PC conventions, but they are frequently used with custom built cables when connecting to non-computer ports.

October 13th, 2002, 11:33 PM	#9
Steve_D Member Join Date: Jul 2002 Location: Albury/Wodonga Posts: 77	Thanks all! After much investigation and with the help of your advice I have established communications...thanks for your time guys.

September 7th, 2003, 11:27 AM	#10
zonix Member Join Date: Sep 2003 Location: ba.ar Posts: 1	RS422 Cable Check this site for RS422 Video information http://www.rs422.com.ar/#Connect_RS422

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