In this appendix:
Status model ........................................................................... C-1
Status model
Overview
Each Keithley Instruments Models 707B and 708B provides a number of status registers and queues
that are collectively referred to as the status model. Through manipulation and monitoring of these
registers and queues, you can view and control various instrument events. You can include
commands in your test program that can determine if a service request (SRQ) event has occurred
and the cause of the event.
The heart of the status model is the Status Byte Register. All status model registers and queues flow
into the Status Byte Register.
The entire status model is illustrated in the Status model diagrams.
Status Byte Register
The Status Byte Register receives summary bits from the other status register sets and queues, and
also from itself (which sets the Master Summary Status, or MSS, bit). For details, see
(on page C-16).
Status register set contents
Typically, a status register set contains the following registers:
•
Condition
(
.condition
): A read-only register that is constantly updated to reflect the present
operating conditions of the instrument.
•
Enable Register
(
.enable
): A read-write register that allows a summary bit to be set when an
enabled event occurs.
•
Event Register
(
.event
): A read-only register that sets a bit to 1 when the applicable event
occurs. If the enable register bit for that event is also set, the summary bit of the register will set
to 1.
•
Negative Transition Register (NTR)
(
.ntr
): When a bit is set in this read-write register, it
enables a 1 to 0 change in the corresponding bit of the condition register to cause the
corresponding bit in the event register to be set.
•
Positive Transition Register (PTR)
(
.ptr
): When a bit is set in this read-write register, it
enables a 0 to 1 change in the corresponding bit of the condition register to cause the
corresponding bit in the event register to be set.
Appendix C
Status model
