Converting RS232-->DH485

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Thread Starter

Agostino Longo

Hey everybody,

I was wondering if I could use a regular rs232-rs485 conv. to interface with a 5/02 processor instead of having to purchase an expensive 1747-PIC. I know I have to get the proper pinouts but i was wondering if anybody out there tried it with any luck?

Thanks.

Agostino Longo
 
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Bhartesh Doshi

Hello Agostino

Well let me tell u first that I dont have any experience in PLCs.
But as far as your question stands u'll have to confirm few things
1) The Data Format (8/9/10 bit) which includes stop bit/parity bit etc.
2) Baud Rate setting (9600, 11500 etc..)

If these two things in particular match with that of the convertor and your 5/02 then i dont think there should be any problem with the conversion.

One more reason to support this statement is that RS-485 / RS-232 are all open standards.. so it wont be necessary to use only a prop. product.

Well one of the convertors which i know and has DIP Switch settings for baud rate and data format is ADAM-4520 from ADVANTECH Ltd. there website is www.advantech.com

Regards
--Bhartesh
 
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Michael Brennan

I agree, PICs stink, but how much does it cost to have wasted time by not having the right tool? Soon, you will see a USB version of the PIC will be available...
 
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Alvin C. Cipriano

Hi, Mr. Agostino Longo

I don't think it will work because the DH485 protocol is a proprietary protocol of Allen Bradley. and I haven't tried it. if you have luck please let me know.

Alvin C. Cipriano
Systems Integration Manager
Mheco Inc.
Authorized S.I. of AB in the Phils.
 
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Hi, Mr. Agostino Longo

My understanding on this is that you are attempting to convert RS-485 to RS-232 signal. can be done, regardless of protocol. there is a signal converter available that will work in both directions, is data TX compliant - meaning when data is presented to the device, it is transmitted, you select the baud rate, all other aspects (parity, stop bit and # of bits - N81) is completely transparent.

The device is the PC-485 made by octagon systems
http://www.octagonsystems.com/AccesPages/pc485.html#

It has changed a little, but we used it a lot to read RS-485 data to a serial port and to also send serial data toa RS-485 device.

They were fairly cheap when I used them about $75.

matt
[email protected]
technical consultants
 
Thanks to everybody that replied, I was going to purchase a SLC 500 with a 5/02 CPU, I decided to pick up a Micrologix 1500 with a few compact I/O modules. It has a built in rs-232 port, more user memory, bigger instruction set and faster processor for a lot less $$.

If anybody wants to try a conventional rs232-rs485 converter in the future keep this in mind. The DH485 pinouts can be easily adapted to the rs485 converter and the communication protocol can easily be modified. Just watchout for the two pins on the SLC 5/02 processor that supply 24Volts. Most converters have there own power supply, AB uses these pins to supply power to the PIC. Could fry your serial port if your not carefull.

Thanks everybody, this is a great site.
 
Someone else metioned that a USB version of the PIC will be available soon... the part number is 1747-UIC. Should be out already but it's not... Rockwell keeps pushing it back.

RS-232 and RS-485 are open protocols, It would not surpise me to see that any convertor would work.
 
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ScienceOfficer

Jfranklin---

The 1747-UIC remains on the plan for release during Fall 2003, not bad for a product that was not planned in January 2003, requires significant software support, and is only needed to support old products on new notebook computers...

The 1747-UIC fills the need for support of SLC500 DH485 products that previously used the 1980s design 1747-PIC, which requires a real RS-232 serial port. Users have always been able to take advantage of the standard RS-485 physical layer of DH485; Rockwell generally referred users to third parties such as Black Box for extenders and level converters. Rockwell never sold the media, and offered very few catalog numbers for the interface. (My condolences to anyone that used the 1784-KR.)

Hope this helps!

Larry Lawver
Rexel / Central Florida
 
I have successfully used a Blackbox port powered converter on the 5/01 and 5/02 processors directly. It no longer worked when attaching through an AIC module. The closest I've tracked down the problem was to a TEN (transmit EN?) wire used on the SLC side.

If anyone wishes to try this, the converter I used was part# IC624A-F . This comes with a RJ45 connector, but you have to open the converter and rearrange the wires to match the RJ45 pins on the processor.
 
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