Your Universal Remote Control Center
RemoteCentral.com
Custom Installers' Lounge Forum - View Post
Previous section Next section Previous page Next page Up level
Up level
The following page was printed from RemoteCentral.com:

Login:
Pass:
 
 

Page 1 of 4
Topic:
RS 232 For Dummies
This thread has 47 replies. Displaying posts 1 through 15.
Post 1 made on Tuesday January 29, 2008 at 00:14
Seatoskytech
Long Time Member
Joined:
Posts:
May 2007
106
OK I really need this book!!!! Any suggestions for someone just starting out with RS 232. Books / Courses / Internet Sites. Looks like i need my trusty lunch kit for school again....
Post 2 made on Tuesday January 29, 2008 at 00:34
Ernie Bornn-Gilman
Yes, That Ernie!
Joined:
Posts:
December 2001
30,104
Yeah, me too. It's been five years, and at that time I just followed instructions.
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
Post 3 made on Tuesday January 29, 2008 at 07:26
skyflyer007
Long Time Member
Joined:
Posts:
July 2004
279
Good luck as there is no industry standard for 232. Everyone has a different way of doing it. There are some samrt guys here and on IP and if you are a URC dealer, Mr. Wagner has some training on their website.
Post 4 made on Tuesday January 29, 2008 at 08:16
Paul_Quadriom
Long Time Member
Joined:
Posts:
September 2007
83
This is the only one I know of..
[Link: marcspages.co.uk]
Post 5 made on Tuesday January 29, 2008 at 09:12
roddymcg
Loyal Member
Joined:
Posts:
September 2003
6,796
On January 29, 2008 at 07:26, skyflyer007 said...
Good luck as there is no industry standard for 232. Everyone
has a different way of doing it. There are some samrt
guys here and on IP and if you are a URC dealer, Mr. Wagner
has some training on their website.

Jeff posted something around here that was very good reading...
When good enough is not good enough.
Post 6 made on Thursday April 14, 2011 at 23:40
SignatureSV
Loyal Member
Joined:
Posts:
July 2009
7,860
Sorry to bring up a way old thread.

But believe it or not the boardroom were doing is my first life experience with RS232...Shocking right? im used to IR and IP control or already terminated RS232

Because im new at this I am completely lost at how to connect The RS232 bare end to the Crestron MPC-M5 Controller. When I striped the cable (one end has the RS232 connector already attached) I found 3 wires wrapped in shielding with a drain wire. On the MPC-M5 terminals I have TX-RX-Grd. So what colors go to what? I assume the drain wire goes to Grd (for ground)

We are using an Optoma HD1060 projector. I saw the RS232 pin out in the manual but im not sure if ill have to adjust the pins on the Terminated End or not.

Thanks all! I appreciate it.

ohh, here is the model number of the cable were using. Its from Crestron CBL-KSERIAL-DB9-L-P-50
The Bitterness of Poor Quality is Remembered Long after the Sweetness of Price is Forgotten! - Benjamin Franklin
Post 7 made on Thursday April 14, 2011 at 23:56
razking
Long Time Member
Joined:
Posts:
February 2011
347
2 is send wire and goes to rcv on the other end
3 rcv (uhm you guess this one)
5 ground - if memory serves. its midnight no the memory is a little shaky.
the drain wire is often not used. that'd be chassis ground.

you may need to reverse 2 and 3 - not having access to your devices pinouts at hand. sometimes they are backwards. this goes back to modems and dumb terminals - of course then the pins were 2,3 and 7 on the db25 connector.

if you can't tell what wire goes to what pin break out your ohm meter.

hope this helps.
You can't make toast in a floppy disk drive.
www.envelopingsound.com
Post 8 made on Friday April 15, 2011 at 00:17
jimmypopali69
Long Time Member
Joined:
Posts:
November 2007
13
Heres the crash course I give ALL my techs on how to terminate rs232, but we always do custom solder ends on boths sides
-Terminate one side
-On other side connect grounds
-check the pins on the wire you just terminated for voltage, one will have between -4 and -11 volts checking from gnd to the other 2 pins, lets call this Line A, we will call the other line B
-check the unterminated side from gnd(p5) to the other 2 pins (2)(3), one will have voltage between -4 and -11 volts, call this pin B, other other pin we will call pin A
-terminate line A to pin a
-terminate line b to pin b
Perfect connections every time, no need to check pinouts**

very rarely neither line will have voltage, check settings to make sure serial is enabled, if it is, you need to check specs on that device, it will say a line is TX, just assume that pin has voltage, and continue as above.
Post 9 made on Friday April 15, 2011 at 00:33
SignatureSV
Loyal Member
Joined:
Posts:
July 2009
7,860
Thanks so far i think i got it. I forget the third color but the two colors OTTOMH are black and red. Is there a standard for colors in RS232?

And drain is generally not connected or used. Got it!
The Bitterness of Poor Quality is Remembered Long after the Sweetness of Price is Forgotten! - Benjamin Franklin
Post 10 made on Friday April 15, 2011 at 01:16
Ernie Bornn-Gilman
Yes, That Ernie!
Joined:
Posts:
December 2001
30,104
On April 15, 2011 at 00:17, jimmypopali69 said...
Heres the crash course I give ALL my techs on how to terminate rs232, but we always do custom solder ends on boths sides
-Terminate one side

That's connect the wires to the pins, right?

-On other side connect grounds

Grounds only? I ask because there's usually one ground.

-check the pins on the wire you just terminated for voltage, one will have between -4 and -11 volts checking from gnd to the other 2 pins, lets call this Line A, we will call the other line B

Whoa.  I'm holding wires connected to a DB9 in my hand, and it'g got voltage on it.  Did you mean, for this test, for me to connect it to the device it will be connected to?

Whoa again. One will have voltage checking from ground to the other two.  This means one will have voltage from ground, the other won't have voltage, right?

-check the unterminated side from gnd(p5) to the other 2 pins (2)(3), one will have voltage between -4 and -11 volts, call this pin B, other other pin we will call pin A

Whoa again.  If I'm checking the unterminated side, then I haven't connected wires to the pins yet, and you want me to check the voltage on the pins.  Did you forget to tell me to plug the connectors in on both ends?
-terminate line A to pin a
-terminate line b to pin b
Perfect connections every time, no need to check pinouts**

very rarely neither line will have voltage, check settings to make sure serial is enabled, if it is, you need to check specs on that device, it will say a line is TX, just assume that pin has voltage, and continue as above.

Can we simplify this a bit by saying that we use pin 5 for ground, and we work it out so that pin 2 on one end goes to pin 3 on the other end; another way to say it is that the wire with voltage coming from the far end goes to the pin that doesn't have voltage on the near end.

As for color code, this can't be defined because the colors on pins 2 and 3 on one end are reversed on the other end.
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
Post 11 made on Friday April 15, 2011 at 02:52
FreddyFreeloader
Super Member
Joined:
Posts:
April 2004
3,243
RS232 is if you work at the local electronics parts store, and you sell anything, connectors or otherwise, with nine pins in it, you know someone is about to have a bad day.

Not necessarily, but sometimes you simply must take a 50/50 shot at the pin out.
Post 12 made on Friday April 15, 2011 at 09:36
39 Cent Stamp
Elite Member
Joined:
Posts:
May 2007
17,515
Solder=old tech that i wont touch. I use RJ45 to DB9 adapters for RS-232.

If i have time to research i will but if not everything gets 23578 connected at both ends. I use a straight RJ45 cable from end to end so it really doesnt matter what the color scheme is but i follow one anyway. If the device isn't being controlled during testing/programming i swap one of the straight RJ45 DB9 adaptors with a 'null pinned" one. This usually gets it working. Occasionally you will run into something different and thats when you have to pull out the manual.

@sig... Usually there is a standard color scheme but i ordered 25 once that had a different color scheme so now i check a few out of each package to make sure they are all the same.
Avid Stamp Collector - I really love 39 Cent Stamps
Post 13 made on Friday April 15, 2011 at 19:57
Ernie Bornn-Gilman
Yes, That Ernie!
Joined:
Posts:
December 2001
30,104
39, I think you're wiring your cables as null cables, and insertion of a null modem adaptor switches the Tx and Rx to the way you should be making them.

That would mean, though, that machines would have to made to switch those wires at one end. That sounds a bit tricky.

Someone please tell me if normal RS232 cables switch Tx and Rx frm end to end.
A good answer is easier with a clear question giving the make and model of everything.
"The biggest problem in communication is the illusion that it has taken place." -- G. “Bernie” Shaw
Post 14 made on Friday April 15, 2011 at 20:09
jimstolz76
Loyal Member
Joined:
Posts:
December 2007
5,607
Straight serial cable is Tx to Tx and Rx to Rx. Null is Tx to Rx and Rx to Tx.

If I understand correctly, in theory one device should be DCE and one is DTE, where the devices are 'expecting' there to be a straight through connection between them.

"The serial port was originally intended to be used for connecting DTE to DCE which makes cabling simple: just use a straight-thru cable. Thus when one connects a modem one seldom needs to worry about which pin is which. But people wanted to connect DTE to DTE (for example a computer to a terminal) and various ways were found to do this by fabricating various types of special null-modem cables. In this case what pin connects to what pin becomes significant."
Post 15 made on Friday April 15, 2011 at 22:43
39 Cent Stamp
Elite Member
Joined:
Posts:
May 2007
17,515
On April 15, 2011 at 19:57, Ernie Bornn-Gilman said...
39, I think you're wiring your cables as null cables, and insertion of a null modem adaptor switches the Tx and Rx to the way you should be making them.

That would mean, though, that machines would have to made to switch those wires at one end. That sounds a bit tricky.

Someone please tell me if normal RS232 cables switch Tx and Rx frm end to end.

I use Cat5 with RJ45 connectors for RS-232. Its a straight 568A cable. Always straight from end to end and pinning is done at the adapter.

I then use RJ45 to DB9 adapters at each end. Both ends are pinned the same 23578 for a straight DB9 cable. So you get continuity if you test pin 2 from end to end. This is a standard serial cable.

2-2
3-3
5-5
7-7
8-8

If the device requires a null modem cable i just remove 1 of the 'straight pinned' DB9/RJ45 adapters and replace it with a 'null pinned' adapter. Now i have a null modem cable.

2-3
3-2
5-5
7-8
8-7

Straight or null cover 99% of the serially controlled/RS-232 devices. Most will work with only pins 2,3&5. I do 7&8 out of habit. I was once told not to connect them unless the manual said to but so far no issues have popped up.
Avid Stamp Collector - I really love 39 Cent Stamps
Find in this thread:
Page 1 of 4


Jump to


Protected Feature Before you can reply to a message...
You must first register for a Remote Central user account - it's fast and free! Or, if you already have an account, please login now.

Please read the following: Unsolicited commercial advertisements are absolutely not permitted on this forum. Other private buy & sell messages should be posted to our Marketplace. For information on how to advertise your service or product click here. Remote Central reserves the right to remove or modify any post that is deemed inappropriate.

Hosting Services by ipHouse