Hi,

I have used the multimedia timer to get better resolution than 55 ms. My ca=
se =

was transmitting on a half duplex RS485 line and I did the turnaround with =
the =

DTR signal. Calculating the time it would take to transmitt and set the =

multimedia timer to this time, when fired switched to receiving with the DT=
R.

Still, I had to set a delay for about 60ms before the receiving microproces=
sor =

could safely reply with it's packet. This was needed to work on W98, 100MHz=
 486 =

computers.

Another option would be to make a hardware switch. Set to TX when the PC sp=
eaks =

and back to RX when it has been silent some time (9 bits if TXing 0x00 (or =
is =

it 0xff?)).

/Ruben


> =

> Thank you Gerhard.
> Can you suggest another control or dll to work around?
> =

> A 10 Bytes packet is sent to a microcontroller. The micro has to replay w=
ith
> another packet. The communication is established at 4800bps Max. Perhaps =
is gone
> to be a smaller bps.
> =

> Since a RF TX module (wen shing) is used to transmit and an RX module is
> used to receive, the DTR line is used to change the antenna from TX to RX
> modules and viceversa, via reed relays.
> Suggestions and experiences are welcome.
> =

> I've set the 1ms VBtimer to switch on and off the DTR line.
> With a scope, the latency measured was 55ms. I think is computer processor
> velocity dependent. But I don=B4t have a lot of computers with window98 to
> demonstrate it.
> Then I've tried a do loop in a form_load event with this code:
> mscomm1.rtsenabled =3D not mscomm1.rtsenabled
> I've got better latencies, 85us!,... until the mouse is moved or whatever
> application is opened!
> Perhaps I must go for another control or dll.
> =

> Anyway thanks for your time.
> Dennis Crawley
> www.geocities.com/proyectosenpic
> =

> =

> =

> =

> =

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=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
Ruben J=F6nsson
AB Liros Electronic
Box 9124, 200 39 Malm=F6, Sweden
TEL INT +46 40142078
FAX INT +46 40947388
ruben@pp.sbbs.se
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
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