Scanning applications, Rules for scanning – Agilent Technologies L4400 User Manual
Page 81
Operating and Programming
3
L4400 User’s Guide
69
The following command clears all user- defined channel labels on the
instrument and restores the factory- default labels.
ROUT:CHAN:LABEL:CLEAR:MOD 1
Scanning Applications
Usage:
•
L4421A 40- Channel Armature Multiplexer
•
L4450A 64- Bit Digital I/O (digital input, counter channels only)
•
L4452A Multifunction Module (digital input, totalizer channels
only)
Channels on selected L4400 series instruments can be “scanned” by
separate devices such as a DMM. During a scan, the instrument channels
are connected to the device and a measurement/reading is made one
channel at a time. Once the measurement is complete, the scan advances
to the next channel in the list until the end of the scan list is reached
and the number of passes (sweeps) through the scan list is complete.
For scanning applications involving the L4421A and a DMM, readings are
stored on the DMM. For applications involving scans of the digital input
and counter channels of the L4450A and the digital input and totalizer
channels of the L4452A, readings are stored in L4450A/L4452A memory.
Scanning is not allowed with the other (L4433A, L4437A, L4445A)
switching instruments. Also, scan lists cannot include digital output
channels or DAC voltage channels.
Rules for Scanning
• Before you can initiate a scan, you must set up a scan list to include
all desired multiplexer or digital channels. Channels which are not in
the scan list are skipped during the scan. By default, channels are
scanned in ascending order. If your application requires non- ordered
scanning of the channels in the present scan list, see
• You can store at least 500,000 scan readings in instrument
(L4450A/L4452A) memory and all readings are automatically time
stamped. If memory overflows, a status register bit is set and new
readings will overwrite the first (oldest) readings stored. The most
recent readings are always preserved. Using the DATA:REMove? or R?
command to retrieve readings during a scan REMOVES the readings
from memory. Using FETCh? after the scan completes retrieves the
readings and the readings also remain in instrument memory.