174 Keysight CXG, EXG, and MXG X-Series Signal Generators Programming Guide
Programming the Status Register System
Accessing Status Register Information
—
The polling method
In the polling method, the signal generator has a passive role. It tells the
controller that conditions have changed only when the controller asks the
right question. This is accomplished by a program loop that continually
sends a query.
The polling method works well if you do not need to know about changes
the moment they occur. Use polling in the following situations:
— when you use a programming language/development environment or
IO interface that does not support SRQ interrupts
— when you want to write a simple, single-purpose program without
the complexity of setting up an SRQ handler
—
The service request (SRQ) method
In the SRQ method (described in the following section), the signal
generator takes a more active role. It tells the controller when there has
been a condition change without the controller asking. Use the SRQ
method to detect changes using the polling method, where the program
must repeatedly read the registers.
Use the SRQ method if you must know immediately when a condition
changes. Use the SRQ method in the following situations:
— when you need time-critical notification of changes
— when you are monitoring more than one device that supports SRQs
— when you need to have the controller do something else while
waiting
— when you can’t afford the performance penalty inherent to polling
Using the Service Request (SRQ) Method
The programming language, I/O interface, and programming environment
must support SRQ interrupts (for example: BASIC or VISA used with GPIB and
VXI-11 over the LAN). Using this method, you must do the following:
1.
Determine which bit monitors the condition.
2.
Send commands to enable the bit that monitors the condition (transition
registers).
3.
Send commands to enable the summary bits that report the condition
(event enable registers).
4.
Send commands to enable the status byte register to monitor the
condition.
5.
Enable the controller to respond to service requests.
The controller responds to the SRQ as soon as it occurs. As a result, the time
the controller would otherwise have used to monitor the condition, as in a loop
method, can be used to perform other tasks. The application determines how
the controller responds to the SRQ.
Summary of Contents for X-Series
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