A8N-E comm port inop.

  • Thread starter Thread starter Howard Delman
  • Start date Start date
H

Howard Delman

I just built up a new system with an A8N-E, Athlon64 3800, &
WinXpProSr2. I cannot get the comm port to work. I use it for various
pieces of electronic hardware, and none can communicate with it.

As the simplest test, I've connected the machine to a single board
computer with a null modem cable. When I start Hyperterm, and try to
connect to the SBC, CPU usage goes to 100%, and my system is almost
totally unresponsive until I can get hyperterm to disconnect. If I move
the cable from this new machine to my old Win98 machine, all works fine.
The old computer and the SBC happily exchange information. I have
configured the com port (com1) on the new machine exactly the same as on
the old machine.

The only other com port on the new machine is a modem, which is assigned
to com4.

Any ideas?

Howard Delman
 
Howard Delman said:
I just built up a new system with an A8N-E, Athlon64 3800, &
WinXpProSr2. I cannot get the comm port to work. I use it for various
pieces of electronic hardware, and none can communicate with it.

As the simplest test, I've connected the machine to a single board
computer with a null modem cable. When I start Hyperterm, and try to
connect to the SBC, CPU usage goes to 100%, and my system is almost
totally unresponsive until I can get hyperterm to disconnect. If I move
the cable from this new machine to my old Win98 machine, all works fine.
The old computer and the SBC happily exchange information. I have
configured the com port (com1) on the new machine exactly the same as on
the old machine.

The only other com port on the new machine is a modem, which is assigned
to com4.

Any ideas?

Howard Delman
Click to expand...

On some other boards, Asus uses Texas Instruments GD75232
RS-232 interface chips. These are old style chips, that
run from +12V and -12V.

http://www-s.ti.com/sc/ds/gd75232.pdf

Is there any possibility that your -12V is out of whack ?

The fact that the new power supplies have no -5V any more,
should not affect a chip like the GD75232.

Also, I notice in the manual, that the A8N-E package
does not come with a serial port adapter plate for a
PCI slot. With third party adapter assemblies, there
are two wiring patterns for the nine pins. The result
is, not all adapter plates will work.

Here is a previous effort to debug an Asus COM port:

http://home.att.net/~Tom.Horsley/p4c800e.html

Paul
 
Paul said:
Also, I notice in the manual, that the A8N-E package
does not come with a serial port adapter plate for a
PCI slot. With third party adapter assemblies, there
are two wiring patterns for the nine pins. The result
is, not all adapter plates will work.
Paul
Click to expand...

My AN8-E (an early model) came with serial port adapter plate for a PCI slot
opening in the rear of the case. I have it hooked up to a 56 kbs US Robotics
modem that I occasionally use for faxing. It works perfectly.

It is described on page 1-27 of the user manual.

Maybe the OP did not hook it up properly to the motherboard header.
 
"Mark A" said:
My AN8-E (an early model) came with serial port adapter plate for a PCI slot
opening in the rear of the case. I have it hooked up to a 56 kbs US Robotics
modem that I occasionally use for faxing. It works perfectly.

It is described on page 1-27 of the user manual.

Maybe the OP did not hook it up properly to the motherboard header.
Click to expand...

OK. I see an adapter pictured here. So that is not the problem.

http://www.newegg.com/Product/ShowI...IA nForce4 Ultra ATX AMD Motherboard - Retail

Paul
 
Paul said:
On some other boards, Asus uses Texas Instruments GD75232
RS-232 interface chips. These are old style chips, that
run from +12V and -12V.

http://www-s.ti.com/sc/ds/gd75232.pdf

Is there any possibility that your -12V is out of whack?
Click to expand...

I've had a 'scope on the Txd and Rxd lines, and they are wiggling at the
right baud rate, and their levels are reasonable. I know the port is
connected, and I know it is being written by software. But clearly...
something is severely messed up.

Howard
 
Howard Delman said:
I've had a 'scope on the Txd and Rxd lines, and they are wiggling at the
right baud rate, and their levels are reasonable. I know the port is
connected, and I know it is being written by software. But clearly...
something is severely messed up.

Howard
Click to expand...

Could it be a serial port interrupt happening over and over
again ? Would a flow control RS-232 signal stuck in the
wrong state do that ?

Paul
 
Paul said:
Could it be a serial port interrupt happening over and over
again ? Would a flow control RS-232 signal stuck in the
wrong state do that ?

Paul
Click to expand...

I have flow control set to "none."

A flailing interrupt would certainly overwhelm the CPU, but that would
be a hardware fault. There is no data being sent, and the various
control lines are inactive, so there is nothing to generate an interrupt.

If you recall my test configuration, I have the comm port connected with
a null modem cable to an rs232 port on a single-board-computer. The SBC
is idling. There is nothing being sent between the machines. But
hyperterm is clearly being overwhelmed by something, and using 99% of
CPU capacity.

Since this is a brand new computer, it is possible that there really is
a hardware fault. But my experience suggests that is very very
unlikely. And I would dread having to rebuild the machine, and to
convince Asus to exchange my board.

Howard
 
Back
Top