DB9 QUESTIONS- LIMITATIONS & QUALITY 3

[Xaqte]

I'm planning on using a DB9 cable that is 150 feet in length. I've already been advised that I would need "low capacitance cable". Anybody have any advise/experience? I know other types of cables require boosters/repeaters, but this doesn't apply to this type of cable- right?

Thanks in advance for all help/suggestions!

X

 

[macphoneguy]

I guess I would say it depends, on the kind of traffic going on it, is it going to be straight RS-232 traffic or something Else ?
a couple of factors, one it the overall distance, two gauge and gauge of wire and number of conductors, third what you are wanting to "Connect" and finally any RF from Lights/motors, talk to the Tech Support of the Equipment you are wanting to connect, if they cannot help Setup a "Dry Run" with the Two pieces of equipment next to each other. (keeping in Mind baud rate, data bits, Parity Etc)
without knowing more Details I would say you would likely need a repeater of some kind,

 

[mradmin]

When you say DB9 cable, I'm guessing you mean a cable with a DB9 connector, probably RS-232 serial. As macphoneguy says, your use depends on many factors. External sources of RF or EMF, the bit rate of the data you wish to send, and what devices you're connecting are the biggest. A few cable manufacturers make "extended-distance" or "extended-distance/Quiet" cables that push the standard limits quite well. I have successfully connected to a "dumb" terminal with over 300 feet of cable, but only at 9600 bps. Some serial printers and industrial control equipment didn't do so well and we had to use line drivers. Let us know more details, we might be able to give a more specific answer.

 

[Xaqte]

This cable connects our Phone system's (Electra Elite 192) ACD card to a PC that runs NEC's ACD + software. This allows us the ability to see phone activity and change ACD configurations. This PC needs to be monitored regularly, and because it is directly connected to the phone equipment we currently have it stationed in the Equipment room (very inconvenient). I need to move it to where it can be accessed easily. I hope this isn't too much details. Thanks again for any help/advice!

X

 

[glister]

The RS232 standard specs a maximum distance of 50 ft.

THESE small devices from B&B Electronics convert between RS232 and RS422 allowing standard computer serial ports to communicate over great distances.

The converters function as an extension of the computer's built-in serial ports, so no software drivers are necessary.

The devices are also compatible with any PC-based operating system. By connecting two serial converters back to back it is possible to extend the distance RS232 equipment can communicate by up to 4000 ft. @ speeds up to 115.2 kbps. No power supply required.

http://www.bb-elec.com/product.asp?sku=422PP9TB&dept_id=166

Category 5 cable is available as shielded twisted pair (STP) as well as unshielded twisted pair (UTP) and generally exceeds the recommendations for RS-422 making it an excellent choice for RS-422.

I've used B&B products for years and have been very pleased.


A+,N+,S+,L+,I+,HTI+,e-Biz+,CETsr,CST,CNST,CNCT,CFOT,CCNT,CCTT,ACSP,ISA CCST3

 

[WinZ]

Q. I Want to use RS-422 Converters to Extend RS-232. How do I Connect them?

http://www.bb-elec.com/tech_articles/faq_422extend.asp

 

[glister]

Fifty feet is commonly quoted as the maximum distance, but this is not specified in the standard. The longer the cable, the greater the cable's capacitance and the slower the speed at which you can obtain accurate results. A large capacitance means voltage changes on one signal wire may be transmitted to an adjacent signal wire.

Maximum length of cables
Baud rate [Bd] Max length [ft] Max length [m]
19,200 50 15
9,600 500 150
4,800 1 000 300
2,400 3 000 900





A+,N+,S+,L+,I+,HTI+,e-Biz+,CETsr,CST,CNST,CNCT,CFOT,CCNT,CCTT,ACSP,ISA CCST3

 

[wires]

Another option is to use a device server to convert serial data to network packets. I have had very good results with Lantronix products. You can either use two device servers to build a dedicated link or a single device server and any PC on the network.

One advantage of device servers is that you use your existing network for the wiring. Another is that any number of PC's on the network can connect to the device (one at a time). This can be very handy for your phone system application since any PC on the network could do the monitoring. The Lantronix redirector software gives the PC the ability to access up to 80 com ports

Here is a sheet that give an overview of one such product.

http://www.lantronix.com/support/docs/pdf/UDS100_PB_910-379.pdf

The full line of device servers from Lantronix is here:

http://www.lantronix.com/products/ds/index.html

Quite a few of these devices show up on eBay.

Lantronix tech support is excellent.

 

[DTSMAN]

I send rs232 over cat5e all the time. We use adapters that go from DB9 to rj45. We have serial printers running well over 150ft. Cables to Go is where I get my adapters. Also by us using these adapters (which never fail) the techs only have to carry cat5 patch cables and customers can find them more easily in a pinch.

 

[daronwilson]

How far you can go will depend on the power of the actual RS232 drivers as well. I've sucessfully done POS and SMDR type connections well over 200 feet on ScTP (Screened Twisted pair) Cat5 or UTP Cat5. Were it me I think i would put in quality shielded cable first and try it before resorting to converters. Some of the RS232 drivers such as those in the good ole Mitel SX-20 PBX could push a fair distance. I've seen some run on a couple pairs of a Cat3 25 pair cable for well over 100 feet in motel installations.

If you need the speed, or can't make it work at RS232 levels, the RS-422/485 converters (often referred to as short haul modems) do a good job for not a whole lot of money.

Good Luck!

Daron J. Wilson, RCDD
daron at wilson dot org

 

[cwc3]

are you using all 9 pins on the db-9
if not you can use db-9 to rj-45s and regular shielded cat 6
and regular cat 6 patch cables and wire i have gone
at least

 

[Xaqte]

Thanks for all the tips/advice! I'm going with daronwilson's tip, I've ran a 125ft low cap db9 cable. I won't actually put it to use for another couple of weeks & I'll post back then with the results.

Thanks,

X

 

[Xaqte]

Daronwilson, you were absolutely right! 125 feet posed no problems!

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