Status Register Sets; Negative And Positive Transition Registers; Status Model - Keithley 3700 series Reference Manual

The Keithley Instruments Series 3700 System Switch/Multimeter provides a number of status
registers and queues that allow the operator to monitor and manipulate various instrument
events. The heart of the status model is the status byte register. This register can be read by the
user's test program to determine if a service request (SRQ) has occurred, and what event
caused the SRQ.

Status register sets

A typical status register set is made up of a condition register, an event register, and an event
enable register (many also have negative and positive transition registers). A condition register
is a read-only register that constantly updates to reflect the present operating conditions of the
instrument. When an event occurs, the appropriate event register bit sets to 1. The bit remains
latched to 1 until the register is reset. When an event register bit is set and its corresponding
enable bit is set (as programmed by the user), the output (summary) of the register will set to 1,
which in turn sets another bit in a lower-level register, and ultimately sets the summary bit of the
status byte register.

Negative and positive transition registers

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In this section:
Status register sets ......................................................................................... 8-1
Status byte and SRQ....................................................................................... 8-2
System summary and status byte .................................................................... 8-3
System summary registers .............................................................................. 8-4
Standard event status register and enable ....................................................... 8-5
Operation events registers............................................................................... 8-5
Questionable event register ............................................................................. 8-6
Measurement event register ............................................................................ 8-6
Status function summary ................................................................................. 8-7
Clearing registers and queues ......................................................................... 8-7
Programming enable and transition registers ................................................... 8-8
Reading registers ............................................................................................ 8-9
Status byte and service request (SRQ) ............................................................ 8-10
Status register set specifics ............................................................................. 8-13
Queues ........................................................................................................... 8-20
Negative-transition register (NTR): When a bit in an NTR register is set by the user,
the corresponding bit in the event register will set when the corresponding bit in the
condition register transitions from 1 to 0.
Positive-transition register (PTR): When a bit in a PTR register is set by the user, the
corresponding bit in the event register will set when the corresponding bit in the condition
register transitions from 0 to 1.
Section 8

Status Model