Giga-tronics 8003, Operation Manual

Page: 179 / 258

Remote Operation
Manual 20791, Rev. C, June 2001 3-37
ments only (no ratios or differences). Every measurement cycle, the analyzer takes a
reading for each active channel (or n readings if the AVG n modifier is specified). Note that
the averaging number may be different for each channel. Whenever the analyzer is talk
addressed, it sends the most recent (averaged) reading from each active channel to the
controller. The OUTPUT command is not required before talk-addressing the analyzer.
Unlike the TØ mode, the T1 mode will send the data for all active channels when talk
addressed. The data returns in the format:
±
ddd.dd,
±
ddd.dd,...,
±
ddd.dd
with one data item for each active channel separated by commas. The T1 mode is
capable of measurement speed in excess of 180 measurements per second.
Fast Bus Triggered CW Mode:
Trigger mode name: T2
This is also a high speed CW reading mode with display updates suppressed. This mode
is very similar to the T1 mode described above except that the analyzer does not free run,
but instead waits for a trigger from the controller. This allows precise timing of measure-
ment events in the system. The trigger is the GPIB Group Execute Trigger (GET)
command. Note that there are both addressed and universal versions of the GET
command so that just the analyzer, or all instruments on the bus can be triggered. When
the trigger is received, the analyzer takes a reading on each active channel (or n readings
if AVG n is specified) and then waits to be talk addressed. When talk addressed, the
analyzer sends each channel’s data to the controller in the serial fashion described above.
Note that in the triggered mode, the 8003 expects the controller to read the data after the
trigger is received. In the Free Run Mode (T1), the controller never needs to read the data.
An additional capability in Triggered Mode is the use of data buffers for each active
channel. Buffering the data allows the analyzer to measure even faster since it does not
have to output the data between readings. Buffering is requested by adding the ITEMS n
modifier to the
POWER command (see the ITEMS modifier under the T2 MODIFIERS
section on page 3-40).
For full GPIB handshaking with buffered measurements, see the SRQ modifier description
under the T2 MODIFIERS section on page 3-40 also.