Specifications

2-9
Programming the HP 71612 Series
Device/Controller Synchronization Techniques
Sequential Commands
Although all commands not listed above as overlapped are sequential, some configuration
changes will take a significant time to complete. While querying a pattern disk catalog
with MNEM:CAT? is essentially self pacing, the completion of operations like
SOURCE1;PATT:UPATn for the selection of disk based user patterns may be conveniently
sensed by following such a command with a *IDN? which, although executing more or
less instantaneously, will not begin execution until all preceding commands have been
completed. Thus when the instrument returns its identification string it will have
completed the configuration of the user pattern.
NOTE Many configuration changes will affect the error detector pattern
synchronization status and a few of these will incur additional settling
time and potentially the need to re-center the detector's clock to data
alignment and/or 0/1 threshold level. Refer to the section entitled
Overview of Control Sequence between Configuration Changes and
the Commencement of Bit Error Measurements, below.
Operation Complete Messages
The following functional criteria are met when an Operation Complete message is
generated:
A SINGLE TIMED gating period has expired.
The automatic eye time-centering operation has expired.
The automatic eye amplitude-centering operation has expired.
An error location capture has occurred.
Overview of Control Sequence between Configuration Changes and the
Commencement of Bit Error Measurements
Whenever the instrument setup is changed, there is a settling time of the hardware and its
controlling firmware that can last seconds, or even minutes for some patterns. When the
instrument is under remote control it is important to hold off following commands until
conditions have settled.
For instance, it would be wrong to start gating whilst the instrument is still settling
because there would be a large spurious error count recorded. Similarly, querying the delta
error count relating to the unit under test, or instructing an oscilloscope to monitor
waveforms should be held off until stability is achieved.
It would not be reliable to use wait statements in the GP-IB control program.