Re: [tlug] Pulse counter over serial port (was RS232)

[Kalin KOZHUHAROV <me.kalin@example.com>]

Hello Henri,

Thank you for the info.

On Mon, Apr 18, 2011 at 11:55, Henri Servomaa <r_muffin@example.com> wrote:
> Kalin KOZHUHAROV kirjoitti 18.4.2011 kello 11.37:
>> On Mon, Apr 18, 2011 at 07:00, Henri Servomaa <r_muffin@example.com> wrote:
>>> Kalin KOZHUHAROV kirjoitti 18.4.2011 kello 3.21:
>>>> As part of a DIY Geiger counter logging backend, I'd like to read
>>>> properly formatted pulses over RS232 on my box (and later on my
>>>> Gumstix).
>>>
>>> Do you mean there's no data protocol, but you just want to read some data value(s) ?
>>>
>> No data protocol, just a 5V pulse/count across two wires, random in
>> time. Usually it is about 100 counts per minute (cpm), but with
>> radiation sources it grows to a few thousand. The software needs to
>> sample say every 10 seconds and see how many counts were there during
>> that time.
>
> Aha.. can you tell me how it's wired? Or point me to HW docs?
>
No docs yet :-|

----------------< GND  (pin 5 on DB-9 female)
-------||-------< RD     (pin 2 on DB-9 female)
       0.01uF

> If I understand this correctly, you will need lower level (not rs232 related) calls to see what the wire status is.
> I can dust off some code/specs later tonight for that.
>
Yep, that is correct, I should have said "Pulse counter over serial port".
According to the description in the code, his geiger was wired like:
 *
 * RM-60     RS-232     DB-25
 * Ground    SG         7
 * Signal    RI         22       [goes low when an event occurs]
 * Positive  DTR        20
 * Negative  RTS        4

So I guess, I can try to rewire it tonight. But if I can change the
software, it will be easier (we are getting quite a good deal on
cables wired this way and they are hot glue fixed). My unit gives a
+5V pulse when event occurs though, so I might need to invert (ouch!)
the signal in hardware...

Any ideas?

Kalin.