from rs232 to rs485

[Guest VZCONTROLES]

AFTER ALL THE COMMUNICATION 1:1 IS QUITE EASY, BUT THE ONLY INCONVINIENCE IS THE DISTANCE (NO LONGER THAN 15 METER). rIGHT NOW I´M TRYING TO CONVERT RS232 TO RS485 TO COMMUNICATE TWO PLC USING 1:1 LINK METHOD. I HAVE A QUESTION ABOUT THE WIRING, CTRL IN IS THE SAME AS RTS? HAVE ANYONE HAS A DIAGRAM TO MAKE THIS CONNECTION. FROM RS232 TO RS485 AND THEN TO RS232. THANKS JORGE

[BobB 58]

Use an Adam 4520 converter at each end. These devices are available from Advantech.

[panic mode 246]

And what is the distance you need?

[Guest curielj]

more or less 25 meters.

[Jay Anthony 118]

I don't think that you will have any problem using RS232 at 25 meters. International standard is 15 meters and that's using non-shielded cable. Just select a good three wire shielded cable and forget the adapters.

[JimRowell 1]

Jay is right. You'll have no problem. The max distance is very arbitrary and depends a great deal on the communication bit rate and noise. Also whether or not you need ultra reliability. You can usually handle the odd error. Transmit back anything received and compare or use hashes or checksums or whatever (or just don't worry about it). Depends on your application. Even shielding is probably not needed although it's always a good idea. You should use properly twisted wire at least. If you decide to change from RS-232, and feel you need 485, you can go with an automatic 485 convertor. These switch between send and receive modes based upon need without being externally commanded. They are very common now. On the non-auto ones, the control line is to select between send and receive modes. You need to operate it in your comm software. It's not the same as 232 control. A better solution is to use RS-422 instead of 485 (unless you need multiple devices sharing the cable ie. more than just one machine at each end). Put an RS-422 convertor at each end, and the two devices will think they are connected in the normal 232 manner. It's 100% compatible. 422 operates the same as 232. It just uses different wiring and different voltage on the 422 side. No change on the 232 side. Very noise resistant. You can even get convertors that can be configured for use as 422 or 485 which is very handy. Some are pricey. Some are cheap. Check around the net and you'll find quite a few. Jim Rowell Edited 5 Mar 2004 by JimRowell

[Fear_me 0]

Thats is what we use and it works without a problem. ~Andrew

[Sleepy Wombat 27]

I've used the ADAM units a lot in the past, and a least they are isolated and give you the connection choice of RS422 and RS485. This is my preferred method also. In regards to Jay's point he is right... in fact i have used the following cable and extended RS232 distance to 80 meter's... The actual claim for ths cable is 150 meters....(RS485 out to 1.4 kM). I believe that the cable may be a Beldon one... but we get it from a company called Blackbox Networing solutions. www.blackbox.com.au Cable Specs... RS-232 Cable, Low-Capacitance, Overall Foil/Braid Shield, Multipair The double-shielded, low-capacitance, low-noise cable for long-distance RS-232 and RS-422 connections. • 24 AWG stranded conductors (7 x 32). • Datalene® insulated with 100% Beldfoil and 65% braid shield. • Low capacitance. • Good crush resistance and lightweight. Item Code RS-232 Cable, Low-Capacitance, Overall Foil/Braid Shield, Multipair 2 Pairs 8102 3 Pairs 8103 4 Pairs 8104 5 Pairs 8105 6 Pairs 8106 7 Pairs 8107 8 Pairs 8108 10 Pairs 8110 121/2 Pairs 8112 15 Pairs 8115 18 Pairs 8118 25 Pairs 8125 Construction: Tinned copper, Datalene insulated, twisted pairs. Overall Beldfoil aluminum-polyester shield. 24 AWG stranded tinned copper drain wire. Overall tinned copper braid shield (65% coverage). Specifications Conductor Gauge — 24 AWG (7 x 32 AWG), stranded Jacket — Chrome PVC Length — 500 ft. (152.4-m); other lengths available Nom. Capacitance* — 12.5 pF/ft. Nom. Impedance — 100 ohms * Capacitance between conductors.

[Guest VZCONTROLES]

The test passed. I could established the commnuication between a cqm1h and a c200he. But I'm still curious I used an entrelec serial link device to convert a rs232 to rs485 but didn't work. It's possible to send me a diagram to make a right connection and a short explanation about every pin? I mean what is rts and the control in of the converter wich pin from the rs232 line must be connect to cntrl in? jorge

[Jay Anthony 118]

Please tell us the Model Number of The Entrelec device and link to the data sheet. We cannot tell you about the pin out until we have the data sheet.

[Guest VZCONTROLES]

the entrelec model is the 84233-11.

[Jay Anthony 118]

From www.klinkmann.com

[Guest curielj]

thanks a lot Jay. If you have documentation about Omron communication, please share it with me. I'm reading a lot of stuff from Omron but in the same way I found a lot of information it produces a lot of questions. I mean information in just one file. jorge

[Guest VZCONTROLES]

I imagined it. If it's possible to send me 2 or 3 of them, I mean If you have them in pdf files or just the reference. jorge

[Jay Anthony 118]

Here's a few at MrPLC.com to get you going: CS/CJ1 Communications Protocols Reference Manual Omron Serial Cables 3G2C7-LK201 and RS232 comm with LSS (and SCADA) 3G2A6-LK201 and RS232 comm with LSS (and SCADA) Sysway Protocol in Espanol

[Guest VZCONTROLES]

THANKS A LOT JAY JORGE