Agilent Technologies L4400 User Manual
Page 98
86
L4400 User’s Guide
3
Operating and Programming
• Two TTL alarm outputs are available on the rear- panel Alarms
connector (Figure 3- 4). You can use these hardware outputs to trigger
external alarm lights, sirens, or send a TTL pulse to your control
system. You can also initiate a scan sweep (no external wiring
required) when an alarm event is logged on a channel. For complete
details, refer to
“Using the Alarm Output Lines"
• A Factory Reset (
*RST
command) clears all alarm limits and turns off
all alarms. An Instrument Preset (
SYSTem:PRESet
command) or Card
Reset (
SYSTem:CPON
command) does not clear the alarm limits and
does not turn off alarms.
• The channel numbering scheme for the digital input and totalizer
channels is shown below.
• Pattern comparisons always start on the lowest- numbered channel in
the bank and extend to all channels involved in the channel width.
• Alarms are evaluated continuously on the digital modules, but alarm
data is stored in reading memory only during a scan.
• Each time you start a new scan, the instrument clears all readings
(including alarm data) stored in reading memory from the previous
scan. However, alarm data stored in the alarm queue from the digital
modules is not cleared. Therefore, although the contents of reading
memory are always from the most recent scan, the alarm queue may
contain data that occurred during previous scans or while the
instrument was not scanning.
To assign the alarm number to report any alarm conditions on the
specified digital input channels, use the following command.
OUTPut:ALARm[1|2]:SOURce (@<ch_list>)
To configure alarms on the specified digital input channel, use the
following commands (also see the example below).
CALCulate
:COMPare:TYPE {EQUal|NEQual},(@<ch_list>)
:COMPare:DATA <data>,(@<ch_list>)
:COMPare:MASK <mask>,(@<ch_list>)
Digital Input Channel
Numbering
Totalizer Channel
Numbering
L4450A
1101 through 1104
1201 through 1204
1301, 1302
L4452A
1001 through 1004
1005