Re: Mark IV Electronics Design

[Chris Albertson <chris@topdog.pas1.logicon.com>]

Griffing, Dan wrote:

> 
> Why not use a high speed LAN interface?
> Then any one of a wide range computers
> with different speeds and operating systems
> with standardized LAN hardware and low level
> vendor-supplied drivers could interface to your
> system.  Alternatively, because Intel Pentium
> PC compatible computers are dirt cheap, you
> could make an entire Mark IV server with a
> LAN interface.

This is very close to how the real-time driver
for the Mk III works.  Well, at least the driver
I've been working on.  I figure I'll adapt it to
the Mk IV and maybe if there is interest, to a few
other non-Droege camera types.  (I have a CB245
so I'll include at least that some day.)

So yes, I've been thinking about "client/server" 
architecture for some time now.  Comes naturally
enough as it is what I've been doing at work sense
the early 1980's  In about 1979 we did this
with a building full of 60-bit CDC mainframes and 
hyperchannel links.

Back to TASS:

What the driver does is read pixels from the 
hardware, store them to disk in FITS format and "push"
them over a socket based interface to a set of
"client" programs.  These clients can do what they
want with the pixels; convert them to web pages,
display on-screen, compute focus, detect clouds
or whatever.  With sockets these "clients" can be on
the same machine, on a LAN or over the Internet.

There is also an "upstream" interface that allows 
clients to make requests and send commands. I have
a very simple "command client" working that allows
a Mk III to be controlled from a remote computer.
Next I'll do a remote display with some "quick look"
analysis features.

The driver also has the ability to interface with
an image processing/data reduction program.  It will
start up an external program with parameters that 
point to each FITS file just after closing the file.
The reduction program could be started
up on a second machine or locally.
The design is flexible enough that it can run all on
one isolated 486 at the command line level or it could
run in a distributed mode on a small set of computers,
real-time displays and all.  The system needs +much+
more work but does run and drive a Mk III.  The
basics are all there.  Source code is on the TASS
web site.

To answer your question directly.  Yes I'd like to 
see the LAN interface move closer to the CCD camera.
IMO the ideal CCD camera head would have a only two 
connectors
1) an ST type fiber connector directly on the camera 
   head that talks 100 megabit/sec Ethernet.
2) 12VDC

If you define the PC as being part of the camera then
you have this setup today, just a bit bulkier that's 
all.  In fact my test computer is a 486/66 8MB with
no monitor or keyboard, just Ethernet.


Dan, I noticed "Staff Software Engineer" after your
name.  If you are looking for a project, drop me a
line.
 
--Chris Albertson

  chris@topdog.logicon.com                Voice:  818-351-0089  X127
  Logicon RDA, Pasadena California          Fax:  818-351-0699