Specifications

Operating Model
The VT1419A card operates in one or two states: either the “idle” state or the
“running” state. The “idle” can be referred to as “Before INIT” and the “running”
state can be referred to as “After INIT.” See Figure 3-3 for the following
discussion.
“Before INIT” positions the card in the Trigger Idle State and its DSP chip is ready
to accept virtually all SCPI commands. This is the time when configuring and set up
operations are performed. This would include linking Engineering Unit conversions
to channels, designating digital input/output channels, downloading algorithms, etc.
“After INIT” (and when trigger events are taking place), the DSP is busy measuring
input channels, executing algorithms, and updating outputs. However, there are
periods of time between trigger events where the DSP is waiting for I/O or just
waiting for the next trigger event. This time is utilized to accept a limited command
set from the supervisory program (Agilent VEE, for example) to change scalars,
arrays/elements or to download new algorithms. Agilent VEE communicates with
the VT1419A’s driver and the driver then interfaces with the DSP, FIFO, CVT,
etc., in cooperation with the operating state. The “When Accepted” comments in the
Command Reference chapter specify which commands may be accepted before or
after INIT.
Programming the VT1419A Multifunction
Plus
Operating Model
52 Chapter 3
Be
f
ore INIT
Commands Accepted:
All commands except:
*TRG, TRIGGER and ALG:UPD:CHAN
After INIT
Commands Accepted:
*RST
ABORt
Most of ALG subsystem
ARM[:IMM]
FETCh?
SENSe:DATA...
STATus...
SYSTem...
*TRG & TRIGger[:IMMediate] (if TRIG:SOUR is HOLD)
Power-On
Trigger Idle
State
INITiate[:IMM]
Waiting for
Trigger State
TIMer or other
trigger event
Input,
Execute Algs,
Output
*RST or ABORt?
Trig Count
Exhausted?
no
yes
no
yes
Figure 3-3: Module States
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