Technical data

Status Registers 3
Programmer’s Guide 23
How to use the Status Registers
A program often needs to detect and manage error conditions or changes
in instrument status. The polling method for you to programmatically
access the information in status registers.
In the polling method, the instrument has a passive role. It only tells the
controller that conditions have changed when the controller asks the
right question. In the SRQ method, the instrument takes a more active
role. It tells the controller when there has been a condition change
without the controller asking. Either method allows you to monitor one
or more conditions.
The polling method works well if you do not need to know about
changes the moment they occur. To detect a change using the polling
method, the program must repeatedly read the registers.
To monitor a condition:
— Determine which register contains the bit that reports the condition.
— Send the unique SCPI query that reads that register.
— Examine the bit to see if the condition has changed.
You can monitor conditions in different ways.
• Check the instrument hardware and firmware status.
Do this by querying the condition registers which continuously monitor
status. These registers represent the current state of the instrument. Bits
in a condition register are updated in real time. When the condition
monitored by a particular bit becomes true, the bit is set to 1. When the
condition becomes false, the bit is reset to 0.
• Monitor a particular condition (bit).
You can enable a particular bit(s), using the event enable register. The
instrument will then monitor that particular condition(s). If the bit
becomes true (0 to 1 transition) in the event register, it will stay set until
the event register is cleared. Querying the event register allows you to
detect that this condition occurred even if the condition no longer exists.
The event register can only be cleared by querying it or sending the
*CLS command.
• Monitor a particular type of change in a condition (bit).