enabling ttyS for rs232 communication

poonippi · 01-19-2008, 05:05 PM

Hi,

I am trying to enable the serial port on IBM 770Z laptop, but I am having trouble detecting it. I think it is ttyS1 as there is the built in modem which I believe is ttyS0, not sure though. Here is some output:

Code:

# setserial -a /dev/ttyS1
/dev/ttyS1, Line 1, UART: 16550A, Port: 0x02f8, IRQ: 3
	Baud_base: 115200, close_delay: 50, divisor: 0
	closing_wait: 3000
	Flags: spd_normal skip_test

Code:

# grep ttyS1 /etc/inittab 
T1:23:respawn:/sbin/getty -L ttyS1 115200 vt100

Code:

# dmesg | grep ttyS
serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a NS16550A
00:03: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A
ttyS0: LSR safety check engaged!
ttyS0: LSR safety check engaged!
ttyS0: LSR safety check engaged!
ttyS0: LSR safety check engaged!
ttyS0: LSR safety check engaged!
ttyS0: LSR safety check engaged!

Included ttyS0, as I thought it might have an adverse affect on the operation of ttyS1.

I plugged a mulitmeter onto the pins of of the rs232 plug, but there is no voltage reading. I also tried copying data to /dev/ttyS1 (which worked on a desktop) but that didn't work either.

Please can some one help us with this.

Thanks very much.

MS3FGX · 01-20-2008, 12:08 PM

I would agree that S0 is more than likely the internal modem, whereas S1 should be your actual external port.

Nothing appears obviously wrong with what your system is showing. Have you checked that it isn't a permissions issue (try echo/catting something to it as root) and that the external port is not disabled in BIOS (common power saving setting on laptops).

poonippi · 01-22-2008, 02:22 AM

Thanks for your reply.

I don't quite know what you mean about permission issues, but here is an echo to ttyS1:

Code:

# echo cat > /dev/ttyS1
bash: echo: write error: Input/output error

...and the permissions for /dev/ttyS1:

Code:

crw-rw----

Also, the TP770 BIOS is absolutely useless, I don't know if I am using it right, but there does not seem to be an options to really do anything! Something called Easy-Step... Yeah, easy if you don't want to do anything!

There is a DB25 connector on the back also, which does have voltages on it! So I may investigate using that instead. But, if you have another solution please let me know.

Regards.

michaelk · 01-22-2008, 09:49 AM

The DB25 connector I assume is a printer port. You might need to configure the laptop with this DOS utility.

http://www-307.ibm.com/pc/support/si...id=RMIE-3AXE3E

poonippi · 01-22-2008, 06:54 PM

Hmmm, interesting. Thanks! Do you think the configuration utility might also help with the DB9 serial port? That would be immense!

Also, I don't have a floppy drive. Looking at the machine, looks like it was traded in for a second battery. I assume the utility would work on a CD? Time will tell..

Cheers.

michaelk · 01-22-2008, 07:47 PM

It should run from a bootable DOS CD. From what I read it should help configure the serial port.

poonippi · 01-23-2008, 03:24 AM

To clarify, I need a bootable DOS CD, right? Does that include the Configuration utility, or does that need anther CD?

Could you point me to a couple of useful URL's on the subject.

Cheers.

michaelk · 01-23-2008, 09:30 AM

You can burn the utility on the same bootable CD.

http://www.nenie.org/misc/flashbootcd.html
http://www.styma.org/bootcdrom/bootcdrom.shtml

BTW Both Nero and Roxio EZ CD creator are able to create a bootable CD if you have these apps handy on a windows PC.