User`s guide

112
Chapter 4 Features and Functions
Scanning with External Instruments
To control scanning with an external instrument, two control lines are
provided. When the 34970A/34972A and the external instrument are
properly configured, you can synchronize a scan sequence between the
two.
In this configuration, you must set up a scan list to include all desired
multiplexer or digital channels. Channels which are not in the list are
skipped during the scan. The instrument automatically scans the list of
channels in ascending order from slot 100 through slot 300.
For an externally-controlled scan, you must either remove the internal
DMM from the 34970A/34972A or disable it (see “Internal DMM Disable”
on page 167). Since the internal DMM is not used, readings from
multiplexer channels are not stored in internal reading memory.
External connections are required to synchronize the scan sequence
between the 34970A/34972A and the external instrument. The 34970A/
34972A must notify the external instrument when a relay is closed and
settled (including channel delay). The 34970A/34972A outputs a Channel
Closed pulse from pin 5 on the rear-panel connector (see previous page).
In response, the external instrument must notify the 34970A/34972A
when it has finished its measurement and is ready to advance to the next
channel in the scan list. The 34970A/34972A accepts a Channel Advance
signal on the External Trigger input line (pin 6).
Channel Closed OUT
34970A/34972A
External DMM
Ext Trig INVM Complete OUT
Ext Trig IN
GND
34970A Refresh UG.book Page 112 Wednesday, February 17, 2010 12:34 PM