AnsweredAssumed Answered

Driver problems

Question asked by VRFuser on Nov 23, 1997
At 11:31 20/11/97 -0500, you wrote:
>Let's try this again   What I am attempting to do is eventually
>control several GPIB instruments from a remote location via socket
>communication.  I would like to use the pre-defined drivers from HP for
>the instrumentation control.  My problem is that using the output
>variables for the respective driver only provide the actual data, for
>example the "CF" variable (center frequency on the HP Spectrum Analyzer
>8562A driver) returns 6000000 from an input of 6M on the driver control
>panel.  I would like it to return CF6000000HZ which is the actual string
>sent to the instrument.  Do I need to alter the driver to do this or is
>there an easier way?
>
>I hope this is a little clearer,
>Allen Lair
>
>

Let me understand your problem.

You have a computer on the LAN in which you run VEE and from where you want
to control/monitor some equipment.
You have other computer on the LAN in which are connected the equipment to
want to manage.

First of all. I think it is much better to use Direct I/O to manage an
equipment.

Basically you have two options, from my point of view. They are:

a) Sockets. You could have two VEE applications running in both computers.
The operator computer (remote computer) should be the socket client. The
equipment computer (local computer) should be the socket server. This system
works fine if you have not some requirements related to the possibility of
stopping one of both applications while the other should be continuing
running. For example, if you stop the server application and the client
still running, you will have communication problems (you will need to
restart the VEE). That means, this system is good for applications that does
not need a high reliability degree.
VEE sockets have other characteristics that have to be into account for your
application.

b) Files. You can send into a file the command to be executed (from operator
computer to the equipment computer). You can send into other file the
command equipment reply (from equipment computer to operator computer).
Files can be sent by means of FTP or by using NFS (one directory for command
files and other for reply files). This system is safer than sockets,
although a little more complex.

In both cases you have to write extra code. However I think it is not very
difficult (we have used both methods).

Does it help to solve your problem?


______________________________________________________

Juan Carlos Martin
E-mail     : jcmar@mdr.indra-espacio.es
Phone      : 34-1-3963995
Fax     : 34-1-3963912
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