Does anybody have any pointers/links for writing RT-LINUX io modules for
the following protocols?

IP/IPX 
OPTO-22
MODBUS-RTU
DirectNET?
RMSM
> GPIB < !!!
TIWAY
SDS I/O
Slice I/O
Others?

Kinda looking for Documentation, RFC's, sample code, been there done
that stories.

Also suggestion as to preferred stable kernels. 2.0, 2.2, or 2.4. Do
kernel OOPs's necessarily kill the RT kernel? Can I do data logging
direct to the disk from RT-kernel without going through the fifo's. So
if the 2.4 kernel crashed, or some user (probably me) ran some wierd
program that locked up the linux-kernel the RT-Kernel keeps on trucking
doing it's job. Can the RT-Kernel watchdog and reboot the linux-kernel
if necessary?

I am intersted in putting together a small distributed analog-to-digital
J-Type thermocouple sampling system of less than 100 points in perhaps
5-10 zones. While daisy chained RS-232/RS-422 will probably carry the
bandwidth for 1 sec samples, the PLC modules I have been looking at are
also ethernet capable (10base-T) for less $. I am thus inclined toward
IP/IPX. Is it reasonable to pay $300.00 to add a nic to a small PLC.
$250 for RS-422.

I am imagining a couple of 5-port ethernet nic's in the RT-LINUX machine
direct connected to a PLC or PLC pair. Maybe two or three RT-LINUX
machines for redundancy/data integrity. 

I have done a cursory examination of the RT-Linux documentation where
ioctl's were added to an ethernet card kernel module. Does this mean
that the Real-Time kernel will get the i/o and interrupt control,
preempting the user space kernel? If I understand what I read correctly
rt-linux gets all of the interrupts first before handing them off to the
linux-kernel. So I should be able to start reading the packets as soon
as they hit the interface coming from the PLC. 

I haven't looked at the serial com driver yet, but I suppose this to be
driven soley by the RT kernel and not accessible to the linux kernel.
This is the way I guess I would like to also program the ethernet
card/s. 

Regards from, Chris.

comments please
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