485 data extraction

[angryman]

Is it possible without knowing much about codewriting, to extract single command data from rs485 comms and, say, use the single command info discretely?

Mark

 

[MacGyverS2000]

Unless you provide more useful data about what you need to accomplish, I see this thread getting locked pretty quickly... so far it sounds like you want to reverse-engineer something that doesn't belong to you.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[angryman]

no no....hardly the case. I have a system that basically opens/closes a gate. The controls are currently done over an RS485 link, and they want to incorporate pushbutton controls without a whole new complete set of wiring....

 

[MacGyverS2000]

Ah, that's useful info...

Disregarding for the moment that two master controllers would be bad (I'll leave that oen up to you to figure out), it's not a bad problem, per se. The "new" master controller (buttons) would use some addressing scheme that wouldn't interfere with data modules currently on the bus. The new "slaves" would understand the addressing scheme and do what they're told.

Your problems seem to be:
1) You want to do this with no code writing (probably impossible)
2) You'll have multiple masters on the line (doable, but you have to get them to work together... typically involves code, but can be done in hardware)
3) Slaves of one type cannot interfere with slaves of the other type (again, involves code)


Dan - Owner

http://www.Hi-TecDesigns.com

 

[angryman]

Yes, that is what I was thinking...I figure I'm either gonna need a code writer(person) or a cheap protocol analyzer (is there such a thing?) or labview, which I'm pretty sure I could do it in, but we do not have labview....

I was approached with this challenge and really need to just verify that I'm not overlooking something simple...I think they are thinking there is some sort of blackbox out there that will allow this, but I cannot find it if so....

Thanks for your input...

 

[Skogsgurra]

Perhaps it is time for you to do some code writing? It is not at all difficult. Kids do it. Have a look at a Basic Stamp or any other "stamp" type small computer. They come with a serial interface (RS232) that can easily be converted (only hardware) to RS485.

These stamps also have parallel I/O. Arrange the stamp to recieve the 485 commands and send them down the line - fully transparent. Then, write a simple code loop that tests the inputs and, if one of the push-buttons is activated, sends the corresponding command. Just do it! You will learn a lot. And you will probably have some fun, too!

A "basic" Basic Stamp won't cost you more than about USD 100. Perhaps less. Add power supply and level converters plus some I/O filters and you will end up with something like USD 200. Then, you may want to make a PCB out of it. That will take a lot more work - and still a couple of 100 dollars. But it can be done at a fairly low cost.

If you approach an engineering company with this, you can probably get it done under USD 2000. It all depends on what they already have in store.

Gunnar Englund

http://www.gke.org

 

[MacGyverS2000]

That sounds like a mini board Keith (itsmoked) would already have on hand, or at least one close enough to make a simple mod to for this application.


Dan - Owner

http://www.Hi-TecDesigns.com

 

[Skogsgurra]

Yes, I would think so. But now, we are close to the thin line: "Promoting, selling, recruiting and student posting
are not allowed in the forums"


Gunnar Englund

http://www.gke.org

 

[angryman]

cool thanks....all I need now is a couple extra days added to the week time time time time

the basic stamp idea is probably an excellent solution, I just need time to play with it...

Thanks again....
Mark

 

[Skogsgurra]

Mark,

I know people that do such things in their spare time. It's called self-teaching...

Gunnar Englund

http://www.gke.org

 

[angryman]

right! I have even less time that is spare than I do at work!

 

[felixc]

Just remember one thing, RS485 is a hardware standard, not a software one. And even as a hardware standard, many are tagging RS485 systems some that are in fact doing RS422. Duplex instead of multidrop party line. So you may discover lots of things with this project. Fun things if you're not subject to a strict timeline, frustrating otherwise...

 

[itsmoked]

Haha, Thanks for the ahem.. cough.. plug Dan.

Sounds like a fun project angryman. A short one with an end in sight unlike some... As skogs sez it's a good little project for someone to "get their feet wet" using a small-off-the-shelf board. It could turn into much more for you opening your horizon a bit.

Here's a link to stamps:

http://www.parallax.com/html_pages/products/basicstamps/basic_stamps.asp

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[angryman]

Thanks Keith,
I'm going to send you a note from your website....

Thanks,
Mark