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Trying to figure out an unknown serial communication protocol, HELP

Posted on 2004-09-11
Medium Priority
Last Modified: 2010-04-17

Iam trying to communicate with some old bowling terminals which as it seems has some serial (DB9) plugs, now what i cant figure out is what baud rate these are running under nor can i find any of the correct setting (stop bit, handshaking and so on). The lanes are of the brand Micronica and some of another brand called Brunswick, can someone help me out here ?

Which communication can it be using when its a serial DB9 plug ( RS-232 or RS-482 right...?) .... ?

Question by:mSchmidt
  • 4

Expert Comment

ID: 12033538
RS-232 doesn't define a connector type. Some standard revisions added connector specs but they're largely ignored by the time a product hits the market. In general, async uses whatever is convenient, fits the panel, and is lowest cost for what works, making it impossible to know design standard from the connector. We might be able to tell given UART support chips, cable types, lengths, and such but which standard is somewhat unimportant unless you suspect differential signals.

A break-out-box or data scope would make things easier by letting you see how the terminals respond to your signals. Barring that, start with a short cable, set for 8/1/none, no handshaking, and roll through the baud rates. If you can't even get garbage then enable hardware handshaking and try again. The equpment may want DTR/RTS/CD before it wakes up and acknowledges your efforts. Let us know what you encounter.


Expert Comment

ID: 12033565
Sorry, too late for complete thoughts.

No manuals of any kind? It would be nice to know the connector pinouts. The connectors could be configured very differently from classic PC-AT serial. Was there any kind of a D9<->D25 adapter or similar with the equipment? That would provide signal clues.

Also, we don't know what "wakes" the terminals. Some UART routines wake up when a hardware handshake signal is received, others with the receipt of data. I'd start by the usual hitting enter at each rate. Ninety + percent of the time you'll find something. If nothing shows even with hardware handshaking enabled it's time to determine pinouts, and that means at least a cheap break-out-box.

Author Comment

ID: 12033593


Micronica System
 Made the system try to connect to the lanes, not having them connected made the system continue trying until it recieved a reply.. My computer didnt reply but simply collected the data
 Ran through all baud rates and got garbage at all baud rates (at least i believe so because i simply created a run through program which logged the information and send it out the other comport and vice versa, meaning if something real was recieved and i submitted this to the lanes they should answer, no answer ever arrived).

Brunswick system
  No reply at any baud rate, havent tried any kind of hand shaking

The problem is that the equipment is located 100 miles from my location, meaning i would like something new to try out the next time i take the trip :)
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Assisted Solution

cyrnel earned 1000 total points
ID: 12033618
Okay, garbage is good. Any idea what a prompt should look like? If you're getting long strings of junk then you probably have the rate too high and are being rolled over with framing errors. If short it can be the reverse, or just the wrong data format. I assume you tried 7/1 & other settings already?

Not knowing your code or the systems, give your program a human touch. UART routines are often sensitive to timing. Change rates, pause a second, send your enter, pause 2 seconds for a response, move on if nothing. If being picky I'll usually drop/pause/raise hardware handshaking between attempts. Sounds like the Brunswick wants something else. Did you find any sign of how they were connected previously? The adapter I was hoping for?

Since the equipment is remote I'd definitely take tools along. Pick up a break-out-box if at all possible. The Brunswick may want handshaking and it's a royal pain to figure out without knowing how it responds. Haven't bought one in a decade but the crusty models were under $10. I'm sure Belkin or similar has them for $toomuch. Once you have that you can see what signals are live, loop back the handshaking, and watch what happens. I'd be happier with a good async terminal program and break-out than with letting a scanner code do its thing, but that's from too long writing termcaps & goofy printer drivers.

Accepted Solution

jimwasson earned 1000 total points
ID: 12034958
I don't know if you can get the right information but Brunswick service manuals are available online here:


If you are looking at much older equipment you might be able to get that information from Brunswick. They offer a document subscription service. Haven't a clue about Micronica, though.

Expert Comment

ID: 12035626
Good catch, jimwasson.

If nothing there or in the install docs sections match it would be worth a call to each company's service depts. A few words with a tech or faxed pages on communications would pretty well resolve this one.

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