BNC 835-3 Programmer Manual - Manual (Page 15)

Berkeley Nucleonics
www.Berkeley Nucleonics.com
835-3
Programmer’s Manual v1.0
Page 15 of 37
The BNC MODEL 835-3 status system consists of the following SCPI-defined status
reporting structures:
•
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.
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 BNC
MODEL 835-3. 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 BNC MODEL 835-3 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