Reading and or Decoding Serial Data

[sodeaf]

Hey Guys,

I was wondering if I could get some input.. I am looking to build add on modules for my Honeywell Home security System. I installed the system myself last year and am pretty educated in that department. As well I have build and played with several picaxe chips using serial in/out from chip to chip. I wouldn't say I found it easy to do, but it also helps when I select the code to send as well as the baud rate and such. I have yet to work with other peripherals other then picaxe using serial in/out.

The Alarm panel I have has several add on module outputs, that use serial to the module to turn lights on and so on.. I want to build a simple module to turn leds on..

Here's the question, And yes I have spend hours searching the net.. with no real solid answer..

What do I need as far as equipment or programs to be able to connect to the serial lines of the alarm panel and read what is being transmitted.??? So I can program my picaxe to look for certain strings of code.. I have a fluke 2 channel scope.. But I don't think that's what I need.. I am willing to download or purchase software, make cables and so on.. I use need your input in regards where to start... suggestions on programs or equipment you have used that works to get the job done.. I don't need anything overkill.. But I have no idea the baud rate or what type of information is being sent or in what manner.. I have 5VDC, GND, TX, RX.. from alarm panel now.. If I touch the screen on alarm panel and select "lights" then On, Off it thinks its sending it to a module.. But there is nothing there... I want my picaxe to answer.. and then do as I ask..


Thanks guys.. I will take your advice seriously and research anything you suggest..


Steve

 

[Buzby]

Hi sodeaf,

This sounds like a really cool project !.

It would be so much easier if you had the protocol for the Honeywell, maybe in a manual somewhere.

If not, then it's a lot of codebreaking work needed.

First thing is to see what the Honeywell is sending out.

Don't start with the Picaxe, just use a Windows terminal app, like HyperTerm or similar, to capture what the Honeywell is sending.

Post that here, and we'll see what we make of it.

Cheers,

Buzby

 

[sodeaf]

Hi sodeaf,

This sounds like a really cool project !.

It would be so much easier if you had the protocol for the Honeywell, maybe in a manual somewhere.

If not, then it's a lot of codebreaking work needed.

First thing is to see what the Honeywell is sending out.

Don't start with the Picaxe, just use a Windows terminal app, like HyperTerm or similar, to capture what the Honeywell is sending.

Post that here, and we'll see what we make of it.

Cheers,




Buzby

Hyper Term?? Now your speaking French.. Is there info on cables and such? How I connect to it??

Thanks

 

[Buzby]

Hyperterm is the terminal programme included in every version of Windows upto XP at least, I've not checked in Win 7 & 8.

It's like the PE Terminal, which you could try, but that's a bit limited on options.

I did a bit of Googling, and it looks like there are a few protocols. We need to know the type and model number of the panel you have to find the right one.

Also, it looks like Honeywell don't release these protocols unless you pay loadsamoney and sign an NDA !.

So this might not really be a suitable project for a newbie with limited serial comms experience.

But if you want to continue I'll do what I can to help.

Cheers,

Buzby

 

[sodeaf]

Ah I see your point.. I just thought there has to be a way to figure it out.. I guess there is.. But people have years of experience with it.. Were I have none!. I am eager to learn and will keep at it until I get it.. I use windows 7 and don't see anything with hyper Terminal... I see there are other programs out there.. But they all cost a ton of cash.. I own and operate a 12 Volt Electronics shop (Car Audio, Remote Starts etc.. ) .. And its full of so many things that use serial communications.. It would be great to start playing around with some gear.. But most of the "Code" is secret and I have no way to acquire it.. other then trying to figure it our on my own..

I pictured in my head : A computer with a program like PE.. with a usb to breakout board with a 5vdc, tx, rx, ground..I would connect the rx wire from pc to the TX wire of device (with a resistor between them?) .. connect common grounds.. When ever a serial transmission happened the computer would read that data and display all information.. Like Baud, parity and data..

Now I guess that would be in a perfect world.. And I could not be so lucky..

hahah

I will keep digging..

Thanks

Steve

 

[srnet]

Whilst it may be a serial protocol, do you know if its compatible with RS232 type serial protocols, start bit, 7 or 8 data bits and a stop bit ?

For a propriety system there is no reason for them to stick to normal standards, and understandable that they dont want to make it easy for third parties to add their own stuff.

I see you live in Canada, so thats OK as I wont hear the alarm, but bear in mind that for a home security network you need to be real sure you fully understand the protocol, your neighbors may not be too happy about false alarms.

 

[Dippy]

I'll start by saying "I don't know" so this is merely food for thought.

Firstly, however, I'd be reluctant to connect directly to a PC as suggested by Buzby.
The Honeywell interface suggests to me that it is looking for 5V TTL style levels and NOT the higher +/- voltages that are likely to be shoved out by a PC serial RS232.

You may need a protecting interface, possibly as simple as the PICAXE download circuit.

Thoughts:-
1. You may need a MAX232 (or transistor) interface for safe connection to a PC plug-hole or a suitable USB-serial thingy.
2. The module may be connected to a UART and therefore it may be looking for a ~5V 'idle' voltage to detect a module has been plugged in. It is possible to fool the main unit just to test.
3. When you say "But there is nothing there", do you mean that no wibbly-wobbly signals appear on your 'scope when you expect the main unit to converse? Nothing?
This may be linked to point (2) above and a pukka MAX232 (if talking to PE terminal) may help.

You're going to have to be careful and methodical for this.
.. and that's before sussing speeds and protocols.
Good luck.

 

[Buzby]

I use windows 7 and don't see anything with hyper Terminal... I see there are other programs out there.. But they all cost a ton of cash..

Hi Steve,

There are hundreds ( well, plenty to choose from, ) free Serial monitor progs and terminals out there on the Net.

I suggest you try a few, and monitor the comms between your two Picaxes to get the feel of what RS232 is and such things as BAUD and stop bits.

You will need to understand this stuff before trying to decode anything, never mind a secret !.

I'm fairly certain the RS232 is 'standard', if there is such a thing as standard with RS232.

It might even be based on the SIA codes, but with proprietary extensions.

What is the model of this panel ?.

Cheers,

Buzby

EDIT : Dippy is right. The port could be '-12v to +12v' or '0v to 5v', and normal or inverse polarity. You need to suss this out before connecting anything to it.

 

[AllyCat]

I have a fluke 2 channel scope.. .. But I have no idea the baud rate or what type of information is being sent or in what manner..

Hi Steve,

Surely the starting point is to look at the waveforms! That will at least tell you the amplitude, polarity, offset voltage, (likely) bit-period and whether it is an "RS232-like" serial protocol. Is it a storage scope?

Post photos of the waveform(s) if necessary, but it you can't work out the basics with a little Googling then I doubt if you've much chance of cracking a (perhaps intentionally) "encrypted" or non-standard, proprietary data protocol. If it looks like an RS232 stream then we can start looking for hardware interface and software monitoring methods.

Cheers, Alan.

 

[g6ejd]

Got access to an oscilloscope? if so that would quickly give you an idea of the data type and voltages and polarity (i.e. 1=+5v or + 12v or 1=-5v or -12.

You could write a short programme on the PICAXE that monitors the line via an input pin every (say) 1mS and stores the result as a series of 0 and 1 in a variable, then use debug to read them out, that would give you an idea of the bit patterns being seen, but could be painfully slow to get to the result you need. e.g.

11111000001111111111 would be a bit stream of 1-0-1-1- with a 1 lasting for 5mS and 0 for 5-mS, etc. Tuning the delay and starting the recording from an edge transition woudl soon get there.

Ideally use a logic analyser.

There may be some free software that does this using a sound card.

 

[sodeaf]

Hey Guys, Thanks a million for the input.. I guess I will have to do some more learning.. and see what i can do.. You have been a great help.. I think I might be a little over my head.. I will start with tested between 2 picaxe and go from there..

Thanks

Steve

 

[geoff07]

Presumably add-on modules come with a spec? That would be a good start.