The Scpi Status Model; What Is An Event Register; What Is An Enable Register - Keysight 34420A User Manual

The SCPI Status Model

All SCPI instruments implement status registers in the same way. The status
system records various instrument conditions in four register groups: the Status
Byte register, the Standard Event register, The Operational Status register, and
the Questionable Data register. The status byte register records high-level
summary information reported in the other register groups. The diagram on the
next page illustrates the SCPI status system used by the meter.
Chapter 6, "Application Programs"
of the status registers. You may find it useful to refer to the programs after reading
the following section in this chapter.

What is an Event Register?

The standard event and questionable data registers have event registers. An event
register is a read-only register that reports defined conditions within the meter.
Bits in the event registers are latched. Once an event bit is set, subsequent state
changes are ignored. Bits in an event register are automatically cleared by a query
of that register (such as *ESR? or STAT:QUES:EVEN?) or by sending the *CLS
(clear status) command. A reset (*RST) or device clear will not clear bits in event
registers. Querying an event register returns a decimal value which corresponds to
the binary-weighted sum of all bits set in the register.

What is an Enable Register?

An enable register defines which bits in the corresponding event register are
logically ORed together to form a single summary bit. Enable registers are both
readable and writable. Querying an enable register will not clear it. The *CLS
(clear status) command does not clear enable registers but it does clear the bits in
the event registers. The STATus:PRESet command will clear the questionable data
enable register. To enable bits in an enable register, you must write a decimal
value which corresponds to the binary-weighted sum of the bits you wish to
enable in the register.
Keysight 34420A User's Guide
Remote Interface Reference
contains example programs showing the use
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