=pod

=head1 National Instruments NI-VISA back-end


The National Instruments NI-VISA library and the associated GPIB drivers are
widely used and proven code for accessing lab devices, and our clear
recommendation for controlling lab devices under Microsoft Windows. For the
respective downloads, please follow the provided links.
Linux support is available, however, installation can be complicated, and there
is no support for USB-GPIB adaptors under Linux. A lot of tips and tricks can
be found at the
L<NI Linux User Forum|http://decibel.ni.com/content/groups/linux-users>.


In general,
L<National Instruments|http://sine.ni.com/psp/app/doc/p/id/psp-411"> offers
excellent documentation. We especially recommend the 
L<NI-VISA User Manual|http://www.ni.com/pdf/manuals/370423a.pdf>, the
L<NI-VISA Programmer Reference Manual|http://www.ni.com/pdf/manuals/370132c.pdf> these references of 
L<VISA resource names|http://zone.ni.com/reference/en-XX/help/371361B-01/lvinstio/visa_resource_name_generic/>
and L<VISA error codes|http://zone.ni.com/reference/en-XX/help/371361B-01/lverror/visa_error_codes/>.


B<< For using the NI VISA library, you will have to install our separate Perl
package L<Lab::VISA> providing the Perl language bindings. Detailed
L<installation instructions|Lab::VISA::Installation> are provided in that
package. >> 

=head1 Linux-GPIB back-end

The L<Linux-GPIB project|http://linux-gpib.sourceforge.net/>  aims at
providing free and open-source hardware drivers and a GPIB library with an API
compatible to the NI drivers (without VISA). The package code is considered
stable and feature-complete; new releases occur mainly as response to changes
in the kernel driver interface. 

=head2 Installing Linux-GPIB

Note that on Gentoo Linux-GPIB is packaged. On distros where this is not the
case, you can use the following steps. For more details, consult Linux-GPIB's
F<INSTALL> file. This guide was tested on Debian 8 with Linux-GPIB versions 4.0.2 and 4.0.3 .

=over

=item * Install the kernel headers, cpanm, gcc and make. On Debian you can run
this command:

 root # apt-get install linux-headers-`uname -r` build-essential cpanminus 

=item * Download the
L<Linux-GPIB sources|http://sourceforge.net/projects/linux-gpib/files/>
 and build with the usual procedure:

 user $ tar -xf linux-gpib-4.0.2.tar.gz && cd linux-gpib-4.0.2
 user $ ./configure
 user $ make

install the library and kernel drivers:

 root # make install

=item * Add your user to the gpib group.

 root # adduser user gpib 

=item * Install the Perl bindings:

 root # cpanm ./language/perl

=back 

=head2 Example Configuration for the GPIB-USB-HS controller

NI's L<GPIB-USB-HS|http://sine.ni.com/nips/cds/view/p/lang/de/nid/201586> is supported out of the box by Linux-GPIB without any
additional proprietary firmware. 

You need a configuration file F</etc/gpib.conf>:

 interface {
        minor = 0       /* board index, minor = 0 uses /dev/gpib0, minor = 1 uses /dev/gpib1, etc. */
        board_type = "ni_usb_b" /* type of interface board being used */
        pad = 0 /* primary address of interface             */
        sad = 0 /* secondary address of interface           */
        timeout = T3s   /* timeout for commands */

        eos = 0x0a      /* EOS Byte, 0xa is newline and 0xd is carriage return */
        set-reos = yes  /* Terminate read if EOS */
        set-bin = no    /* Compare EOS 8-bit */
        set-xeos = no   /* Assert EOI whenever EOS byte is sent */
        set-eot = yes   /* Assert EOI with last byte on writes */

 /* settings for boards that lack plug-n-play capability */
        base = 0        /* Base io ADDRESS                  */
        irq  = 0        /* Interrupt request level */
        dma  = 0        /* DMA channel (zero disables)      */


        master = yes    /* interface board is system controller */
 }


To load the kernel driver during boot, add C<ni_usb_gpib> to
F</etc/modules>. 

After connecting the controller via usb, you will still have to run
C<gpib_config> as root. To automate this, create an udev rule
F</etc/udev/rules.d/98-gpib-more.rules> with contents:
 
 SUBSYSTEMS=="usb", ATTRS{idVendor}=="3923", ATTRS{idProduct}=="709b" ACTION=="add", RUN+="/usr/bin/logger Configured NI USB-GPIB-HS" RUN+="/etc/hotplug/usb/ni_usb_gpib"


Now, you can use the interactive C<ibtest> and C<ibterm> programs to test the installation.



