Agilent Technologies HP 82335, Install Manual, Page: 49 / 54

Using Fast Talker Mode with the
HP
82341
The HP
82341
high performance HP-m card is capable of high-speed HP-IS
operation while using HP SICL, but only under the conditions specified by
the
IEEE
488 specification for such operation. To turn on Fast Talker mode,
use the following SICL function:
igpibsettldelay
{ imf_id,
I_GPIB_TIDELAY_MINl
i
This will turn on Fast Talker mode for all session attached
[0
the interface
specified by
intf_id.
To turn Fast Talker mode off, use the following SICL function:
igpibsettldelay
( intf_id.
I_GPIB_TIDELAY_MAX ) ;
For more information, refer to
igpibgettldelay
and
igpibsettldelay
in the
HP SICL
Reference
Manual.
The critical parameter is the so-called ''T 1 delay," or settling time for multi­
line messages, as defined in the
IEEE 488
specification. The specified value
for this parameter is 2 microseconds minimum. However, it can be reduced to
350 nanoseconds minimum if the following special considerations arc met:
• The device capacitance per line (except for REN and IFC) should be less
than 50 picofarads per device. This requires the use of tri-state electrical
HP-lE drivers, instead of open-collector HP-lE drivers.
While it is difficult to determjne this specification unless it is published
for a particular instrument, in practice devices designed for fast operation
will meet the specification. It can be assumed that a device not specified
for fast operation will not meet it.
•
All devices in the system should be powered-up.
•
The total length of HP-IB cables connected to the HP-IB interface should
be no more than
15 meters, and there should be one device for each meter
(or less) of cable.
If these specifications are not met by all devices on the interface, reliable
high-speed operation cannot be guaranteed.
In practice, this means that a system where speed is of critical importance may
require the use of
two HP-ill cards: one for slow-speed operation with most of
the accessory devices, and one with only the fast device(s) on it for high-speed
operation.
40 AppendixB