B&K Precision MDL Series - Programming Manual - Manual (Page 14)

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Condition registers
All status register sets have a condition register. A condition register is a real-time, read-only register
that constantly updates to reflect the current operating conditions of the instrument.
Use the :CONDition? query commands in the STATus Subsystem to read the condition registers. See
Chapter 3 for more information.
Event registers
Each status register set has an event register. An event register is a latched, read-only register whose
bits are set by the corresponding condition register. Once a bit in an event register is set, it remains set
(latched) until the register is cleared by a specific clearing operation. The bits of an event register are
logically ANDed with the bits of the corresponding enable register and applied to an OR gate. The
output of the OR gate is applied to the Status Byte Register.
Use the *ESR? Common Command to read the Standard Event Register. All other event registers are
read using the :EVENt? query commands in the STATus Subsystem. See Chapter 3 for more
information.
An event register is cleared when it is read. The following operations clear all event registers:
• Cycling power
• Sending *CLS
Enable registers
Each status register set has an enable register. An enable register is programmed by you and serves as
a mask for the corresponding event register. An event bit is masked when the corresponding bit in the
enable register is cleared (0). When masked, a set bit in an event register cannot set a bit in the Status
Byte Register (1 AND 0 = 0). To use the Status Byte Register to detect events (i.e., serial poll), you must
unmask the events by setting (1) the appropriate bits of the enable registers. To program and query
the Standard Event Status Register, use the * ESE and *ESE? Common Commands respectively. All other
enable registers are programmed and queried using the :ENABle and :ENABLe? commands in the
STATus Subsystem. See Chapter 3 for more information.
An enable register is not cleared when it is read. The following operations affect the enable registers:
• Cycling power clears all enable registers
• :STATus:PREset clears the following enable registers:
o Operation Event Enable Register
o Questionable Event Enable Register
o Channel Summary Event Enable Register
• *ESE 0 clears the Standard Event Status Enable Register.
Output queue
The output queue holds data that pertains to the normal operation of the instrument. For example,
when a query command is sent, the response message is placed on the output queue.