Agilent Technologies N5181A/82A User Manual download pdf (Page 159)

Agilent N518xA, E8663B, E44x8C, and E82x7D Signal Generators Programming Guide 149

Programming the Status Register System

Accessing Status Register Information

1. Determine which register contains the bit that reports the condition. Refer to Figure 4- 1 on

page 140 through Figure 4- 8 on page 147 for register location and names.

2. Send the unique SCPI query that reads that register.

3. Examine the bit to see if the condition has changed.

Determining What to Monitor

You can monitor the following conditions:

• current signal generator hardware and firmware status

• whether a particular condition (bit) has occurred

Monitoring Current Signal Generator Hardware and Firmware Status

To monitor the signal generator’s operating status, you can query the condition registers. These

registers represent the current state of the signal generator and are updated in real time. When the

condition monitored by a particular bit becomes true, the bit sets to 1. When the condition becomes

false, the bit resets to 0.

Monitoring Whether a Condition (Bit) has Changed

The transition registers determine which bit transition (condition change) should be recorded as an

event. The transitions can be positive to negative, negative to positive, or both. To monitor a certain

condition, enable the bit associated with the condition in the associated positive and negative

registers.

Once you have enabled a bit via the transition registers, the signal generator monitors it for a change

in its condition. If this change in condition occurs, the corresponding bit in the event register will be

set to 1. When a bit becomes true (set to 1) in the event register, it stays set until the event register

is read or is cleared. You can thus query the event register for a condition even if that condition no

longer exists.

To clear the event register, query its contents or send the *CLS command, which clears all event

registers.

Monitoring When a Condition (Bit) Changes

Once you enable a bit, the signal generator monitors it for a change in its condition. The transition

registers are preset to register positive transitions (a change going from 0 to 1). This can be changed

so the selected bit is detected if it goes from true to false (negative transition), or if either transition

occurs.

Deciding How to Monitor

You can use either of two methods described below to access the information in status registers (both

methods allow you to monitor one or more conditions).

• 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.

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Agilent Technologies N5181A/82A User Manual Page 159