Agilent Technologies USB/GPIB Interface Converter 82357A - Manual (Page 41)

Chapter 2 41
Using the 82357A
Setting Configuration Parameters
Setting 82357A High-Performance Operation
Introduction
The GPIB transfer rate for 82357A writes using large (>1000 bytes) buffer
size is affected by the Data Available (T1) delay time. (The transfer rates are
not noticeably affected when the buffer size is <1000 bytes). The default
delay time used by the 82357A is 800 nsec.
The maximum transfer rate for T1 = 350 nsec is about 900 KBytes/sec as
compared to about 650 KBytes/sec for the 82357A default value of 800
nsec. Changing the T1 delay affects ONLY the write performance of the
82357A.
Setting T1 Value
With VISA
To set the T1 value with VISA, use the VI_AGATTR_GPIB_T1_DELAY
attribute. The VI_AGATTR_GPIB_T1_DELAY value is the time of the T1 delay in
nanoseconds, and should be no less than VI_AG_GPIB_T1DELAY_MIN
or no greater than VI_AG_GPIB_T1DELAY_MAX . This value is defined in
Agilent's 'visa.h' header file. To use this value, you must ' #define
AGVISA_ATTRIBUTES ' before the ' #include "visa.h " in your C or C++ source
file.
The 82357A supports T1 delays from 350 nsec to <max_value> in steps of
40 nsec. You can find out the actual value by calling
viGetAttribute() .
Setting T1 Value
With SICL
To set the T1 value with SICL, use the igpibsett1delay() command and
modify the GPIB environment. For further information, you may want
to see the Hewlett-Packard document “Tutorial Description of the Hewlett-
Packard Interface Bus”. See Section 2.12, Optimizing Performance.
NOTE
Changing the T1 delay as described in this section is an advanced
feature and also requires attention to cable lengths and other system
features.
Attribute Access Priv. Data Type Range (nsec) Used By
VI_AGATTR_GPIB_
T1_DELAY RW Global ViInt32 VI_AG_GPIB_T1DELAY_MIN to
VI_AG_GPIB_T1DELAY_MAX GPIB INTFC
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