VXI VT1422A - Manual (Page 150)

148 Programming the VT1422A for Data Acquisition and Control Chapter 4
Reading Status
Groups Directly
It may be desirable to directly poll status groups for instrument status rather
than poll the Status Byte for summary information.
Reading Event Registers
The Questionable Data, Operation Status and Standard Event Groups all
have Event Registers. These Registers log the occurrence of even temporary
status conditions. When read, these registers return the sum of the decimal
values for the condition bits set, then are cleared to make them ready to log
further events. The commands to read these Event Registers are:
STAT:QUES:EVENT?
Questionable Data Group Event
Register
STAT:OPER:EVENT?
Operation Status Group Event
Register
*ESR?
Standard Event Group Event
Register
Clearing Event Registers
To clear the Event Registers without reading them, execute:
*CLS
clears all group’s Event
Registers
Reading Condition
Registers
The Questionable Data and Operation Status Groups each have a Condition
Register. The Condition Register reflects the group’s status condition in
"real-time." These registers are not latched so transient events may be
missed when the register is read. The commands to read these registers are:
STAT:QUES:COND?
Questionable Data Group
Condition Register
STAT:OPER:COND?
Operation Status Group
Condition Register
VT1422A Background Operation
The VT1422A inherently runs its algorithms and calibrations in the
background mode with no interaction required from the driver. All resources
needed to run the measurements are controlled by the on-board Control
Processor (DSP).
The driver is required to setup the type of measurement to be run, modify
algorithm variables and to unload data from the card after it appears in the
CVT or FIFO. Once the INIT[:IMM] command is given, the VT1422A is
initiated and all functions of the trigger system, measurement scanning,
and algorithm execution are controlled by its on-board control processor.
The driver returns to waiting for user commands. No interrupts are required
for the VT1422A to complete its measurement.
While the module is scanning and/or running algorithms, the driver can
be queried for its status and data can be read from the FIFO and CVT.
The ABORT command may be given to force continuous execution to
complete. Any changes to the measurement setup will not be allowed until
the TRIG:COUNT is reached or an ABORT command is given. Of course,
any commands or queries can be given to other instruments while the
VT1422A is running algorithms.