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Appendix E, ALPHABETICAL LISTING OF COMMANDS
TDT n
TRIGOUT [n]
TRIGOUTPOL [n]
USBTERM [n]
E-24
Take data triggered
Sets the instrument so that data acquisition is initiated on receipt of various trigger
conditions at the TRIG connector on the rear panel. If an oscillator frequency and/or
amplitude sweep has been defined and linked to the curve buffer using the SWEEP
command with a parameter of 9, 10 or 11, then this sweep will be started as well.
There are two basic triggers. The Acquisition trigger is a "per curve" (start) or "per
point" (sample) trigger and can be active on either the rising or falling edge. The
Stop trigger sets the condition by which acquisition finishes. In normal operation this
is simply when the number of points specified by the LEN command parameter have
been acquired, but it is also possible to leave acquisition running until an HC
command is sent or until either a rising or falling edge occurs at the trigger input.
The trigger modes, set by the value of n, are as follows:
n
Start condition
0
Ext rising edge
1
On command
2
Ext falling edge
3
On command
4
Ext rising edge
5
On command
6
Ext falling edge
7
On command
8
Ext rising edge
9
Ext falling edge
Note that in modes 1, 3, 5 and 7 the maximum trigger rate is 1000 Hz and the storage
interval control setting has no effect.
Curve buffer trigger output
The value of n defines the type of trigger output generated when a buffer acquisition
is run in accordance with the following table:
n
Trigger
0
Trigger generated once per curve, at start of curve
1
Trigger generated once per point
Curve buffer trigger output polarity
The value of n defines the polarity of the trigger output generated when a buffer
acquisition is run in accordance with the following table:
n
Trigger Output
0
Rising-edge
1
Falling edge
Set/read USB terminator
The value of n sets the USB terminator according to the following table:
n
Function
0
A null character (ASCII 0)
1
A null character (ASCII 0), followed by a byte representing the value of the
status Byte (table 6-1), followed by a byte representing the value of the Overload
Byte (table 6-1)
Sample condition
-
Ext rising edge
-
Ext falling edge
-
Ext rising edge
-
Ext falling edge
-
-
Stop condition
Points = LEN
Points = LEN
Points = LEN
Points = LEN
On HC command
On HC command
On HC command
On HC command
Ext falling edge
Ext rising edge
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