BNC 835 Programmer Manual - Manual (Page 19)

Berkeley Nucleonics Corporation 2955 Kerner Blvd., San Rafael, CA 94901
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• The Instrument Summary Status Byte
• The Standard Event Status Group
• The Operation Status Group
• The Questionable Status Group
The following paragraphs describe the registers that make up a status group and explain the status
information that each status group provides.
4.6 Status Registers
In general, a status group consists of a condition register, a transition filter, an event register, and an
enable register. Each component is briefly described in the following paragraphs.
Condition Register
The condition register is continuously updated to reflect the current status of the BENCHTOP
MICROWAVE SOURCE. There is no latching or buffering for this register, it is updated in real time.
Reading the contents of a condition register does not change its contents.
Transition Filter
The transition filter is a special register that specifies which types of bit state changes in the condition
register will set corresponding bits in the event register. Negative transition filters (NTR) are used to
detect condition changes from True (1) to False (0); positive transition filters (PTR) are used to detect
condition changes from False (0) to True (1). Setting both positive and negative filters True allows an
event to be reported anytime the condition changes. Transition filters are read-write. Transition filters
are unaffected by queries or *CLS (clear status) and *RST commands. The command
:STATus:PRESet sets all negative transition filters to all 0’s and sets all positive transition filters to all
1’s.
Event Register
The event register latches transition events from the condition register as specified by the transition
filter. Bits in the event register are latched, and once set they remain set until cleared by a query or a
*CLS command Event registers are read only.
Enable Register
The enable register specifies the bits in the event register that can produce a summary bit. The
BENCHTOP MICROWAVE SOURCE logically ANDs corresponding bits in the event and enable
registers, and ORs all the resulting bits to obtain a summary bit. Summary bits are recorded in the
Summary Status Byte. Enable registers are read-write. Querying an enable register does not affect it.
The command :STATus:PRESet sets the Operation Status Enable register and the Questionable
Status Enable register to all 0’s.