On Sat, 19 May 2018 13:41:35 +0100, Dave Liquorice wrote:

> This is probably very close to a saying involving Grandmas and eggs but:
>
> Is the KRT2 also a three wire device (Tx, Rx, Gnd)?
>
Yes, it is.

> As the AXE027 is designed for a PICAXE is it using TTL 0 - 5 V signal
> levels or proper RS232 +/- 12 V? What does the KRT2 expect?
>
Good point and one I didn't think of but should have - I'm too used to
stuff that works on either TTL or 12v.

The AXE027 is almost certainly TTL level since PICAXE chips are happy on
nominal 4.5v supplies (3 x AA cells).

The KRT2 manuals don't say what signal levels are expected on the serial
port. The radio runs off 9-28v (mine is on a 12v SLA) but the manuals say
nothing about serial port levels. It is (used for both presets up/down
load and to connect to an optional remote control head). The manuals I
have include one for the presets up/download connection, but that expects
the PC to have an RS-232 serial port and, again, doesn't mention the
expected signal level.

> Can you monitor the Tx and Rx an lines and see if data is being sent on
> either. A LED with series resistor from each line to Gnd will do. Once
> you know that the hardware is playing you know for certain that you have
> a software problem of some sort.
>
Thats difficult logistically, but I think I can get a scope on the lines,
which may be easier than powering a logic probe or adding LEDs. The logic
probe would be my favoured weapon but I'm not sure where I'd get its
power from in this case. The KRT2 crams all its connections onto a D-15
and the resulting cable connections (power, PTT, mic, speaker, serial
lines) have filled its cover to bursting point).

If needed, I have another USB adapter but its an older pfranc unit and I
don't know what its serial signal levels are either. USB-serial adapters
are obviously running off 5v, but do they normally provide 12v or TTL
levels on their RS232 pins?

Anyway, thanks for pointing out an obvious point I'd overlooked.

I'll ask the local agent about signal levels on Monday.


--
Martin    | martin at
Gregorie  | gregorie dot org

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