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9640A
Instruction Manual
Status Event Registers
Use the following queries to read the Status Event registers:
*ESR? reads the Standard Event Status register
:STATus:OPERation? reads the Operation Status Event register
:STATus:QUEStionable? reads the Questionable Status Event register
Reading one of these registers will clear the register and the summary message bit in the
status byte.
To clear all event registers use the *CLS (Clear Status) command.
Status Condition Registers
Two of the status register structures also have condition registers: The Status Operation
and the Status Questionable register.
The condition registers differ from the event registers in that they are not latched. That is,
if a condition in the Instrument goes on and then off, the condition register indicates true
while the condition is on and false when the condition goes off. The Event register that
monitors the same condition continues to indicate true until you read the register.
:STATus:OPERation:CONDition? reads the Operation Status Condition register
:STATus:QUEStionable:CONDition? reads the Questionable Status Condition
register
Reading the condition register will not affect the contents of the register.
Summary
The way to work when writing your bus program is as follows:
Set up
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Check & Action
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4B-20
Set up the enable registers so that the events you are interested in are summarized in
the status byte.
Set up the enable masks so that the conditions you want to be alerted about generate
SRQ. It is good practice to generate SRQ on the MAV bit. So, enable the MAV-bit
via *SRE.
Check if an SRQ has been received.
Make a serial poll of the instruments on the bus until you find the instrument that
issued the SRQ (the instrument that has RQS bit true in the Status Byte).
When you find it, check which bits in the Status Byte Register are true.
Let's say that bit 7, OSS, is true. Then read the contents of the Operation Status
Register. In this register you can see what caused the SRQ.
Take appropriate actions depending on the reason for the SRQ.
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