Keithley 2016 - Figure 4-9 Questionable Event Status; Output Queue; Queues

Queues
The Model 2016 uses two queues, which are first-in, first-out (FIFO) registers:
• Output Queue - used to hold reading and response messages
• Error Queue - used to hold error and status messages
The Model 2016 THD Multimeter status model (Figure 4-5) shows how the two queues are
structured with the other registers.
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.
When data is placed in the Output Queue, the Message Available (MAV) bit in the Status Byte
Register sets. A data message is cleared from the Output Queue when it is read. The Output
Queue is considered cleared when it is empty. An empty Output Queue clears the MAV bit in
the Status Byte Register.
Read a message from the Output Queue by addressing the Model 2016 THD Multimeter to
talk after the appropriate query is sent.
(B13 - B9)
(B14) (B8)
(B15)
OR
Questionable
Condition Register
Questionable Event
Enable Register
Warn = Command Warning
Cal = Calibration Summary
Temp = Temperature Summary
& = Logical AND
OR = Logical OR
PTR = Positive Transition Register
NTR = Negative Transition Register
&
&
&
0
(B13 - B9)
(B14)
(B8)
(B15)
0
Warn Cal
Questionable Event
Register
(B13 - B9)
(B14) (B8)
(B15)
To Questionable
Summary Bit (QSB)
of Status
Byte Register
(See Figure 4-10).
(B7 - B5)
(B7 - B5)
(B7 - B5)
Warn Cal
0
Warn Cal
(B4)
Temp
(B4)
Temp
(B3 - B0)
(B3 - B0)
(B3 - B0)
(B4)
Temp
&
Fi
gure
4
-
9
Questionable
event status
4-20 Remote Operation