Keithley 237

2.22.2 Input Trigger Origin
The source (origin) of input triggers is defined by this
trigger setup.
Input trigger origin selections (summa-
rized in Table 2-13) are described as follows:
Internal
Origin
With this trigger origin selected, an input trigger will oc-
cur
when the front panel MANUAL trigger button is
pressed or the HO command is sent over the IEEE-488
bus.
External
Origin
With this trigger origin selected, an input trigger will oc-
cur when a
TTL level pulse (see Figure 2-51) is applied to
the TRIGGER IN connector (BNC) of the Source Measure
Unit (see Figure 2-52)
by an external instrument. This in-
put trigger will cause the Source Measure Unit to per-
form one
or more operations.
Also,
an input trigger will occur when the front panel
MANUAL trigger button
is pressed or the HO command
is sent over the IEEE-488 bus.
IEEE TALK Origin
With this trigger origin selected, an input trigger will oc-
cur
when the Source Measure Unit is addressed to talk
over the
IEEE-488 bus. Also, an input trigger will occur
when the
HO command is sent over the IEEE-488 bus, or,
if in local operation, when the front panel MANUAL trig-
+
Triggers on
SECTION2
Operation
----.., Falling Edge ------
TTL High
(2V-5V)
TTL Low
(OV- 0.8V)
1.- 10~ -.1
1 Minimum 1
Figure 2-51. External Input Trigger Pulse Specification
ger button is pressed. See Section 3 for complete informa-
tion.
IEEE GET
Origin
With this trigger origin selected, an input trigger will oc-
cur
when a group execute trigger (GET) is sent over the
IEEE-488 bus. Also,
an input trigger will occur when the
HO command is sent over the IEEE-488 bus, or, if in local
operation,
when the front panel MANUAL trigger but-
ton
is pressed.
IEEE X Origin
With this trigger origin selected, an input trigger will oc-
cur
when an "X" is sent over the IEEE-488 bus. Also, an
input trigger will occur when the HO command is sent
over the IEEE-488 bus, or,
if in local operation, when the
front panel MANUAL trigger button
is pressed.
Table 2-13. Input Trigger Origin
Selection
Trigger
Stimulus
INTERNAL ORIGIN Front panel MANUAL trigger button or HO command over IEEE-488 bus.
EXTERNAL ORIGIN
Negative-going
TTL level pulse applied to TRIGGER IN connector.
IEEE TALK
ORIGIN
Unit addressed to talk over IEEE-488 bus.
IEEE GET ORIGIN
Group execute trigger
(GET) command sent over IEEE-488 bus.
IEEE X ORIGIN "X" sent over IEEE-488 bus.
+
2-87