Losing data in serial communication (in QNX 4.25);

I’ve got two computers ( one with QNX 4.25 and one with QNX 6.3.2 )
connected with each other by RS-232
(3 wire: rx, tx, gnd; 2m long; no handshaking; 115200-8-N-1).

Serial communication ( /dev/ser/1 read() / write() )
works fine on QNX 6.3.2,
but QNX 4.25 is losing received data (tx is ok).

I try to set higher priority ( setprio() )
and increase stop bits to 2,
but the data is still losing, event at 38400-8-N-2 .

What is wrong ?

/the program works fine @115200,8,N,1
between QNX 6.3.2 - QNX 6.3.2
and beetween QNX 6.3.2 - Windows XP;

How fast is your QNX 4.25 box?
What else is running on it?

“Q” <no@spam.pl> wrote in message news:ehiafl$emo$1@inn.qnx.com

I’ve got two computers ( one with QNX 4.25 and one with QNX 6.3.2 )
connected with each other by RS-232
(3 wire: rx, tx, gnd; 2m long; no handshaking; 115200-8-N-1).

Serial communication ( /dev/ser/1 read() / write() )
works fine on QNX 6.3.2,
but QNX 4.25 is losing received data (tx is ok).

I try to set higher priority ( setprio() )
and increase stop bits to 2,
but the data is still losing, event at 38400-8-N-2 .

What is wrong ?

/the program works fine @115200,8,N,1
between QNX 6.3.2 - QNX 6.3.2
and beetween QNX 6.3.2 - Windows XP;

How fast is your QNX 4.25 box?

all are fast enoguh :slight_smile:, especially for serial communications :slight_smile:.

QNX 4 is on SBS PC7 Compact (Celeron 566 MHz + 128 MB RAM),

QNX 6 and WinXP are on “normal” :slight_smile: computers -

  • Asus MotherBoard + Celeron 3 GHz + 1024 MB RAM + …

“Q” <no@spam.pl> wrote in message news:ehil24$lcp$1@inn.qnx.com

How fast is your QNX 4.25 box?

all are fast enoguh > :slight_smile:> , especially for serial communications > :slight_smile:> .

QNX 4 is on SBS PC7 Compact (Celeron 566 MHz + 128 MB RAM),

Have you tried -t option of Dev.ser?

QNX 6 and WinXP are on “normal” > :slight_smile: > computers -

  • Asus MotherBoard + Celeron 3 GHz + 1024 MB RAM + …

Have you tried -t option of Dev.ser?

Dev.ser -t 14 &

thanks for solving my problem :slight_smile:

Q wrote:

Have you tried -t option of Dev.ser?


Dev.ser -t 14 &

thanks for solving my problem > :slight_smile:

Yes, must turn on the FIFO, or the main CPU has to service
every character within one character time. With “-t 14”, it
has 14 character times to catch up.

You might also check that on your QNX 6 box; even if it can
keep up, it’s working way too hard doing all those serial interrupts.

John Nagle