Agilent Technologies L4400 manual OUTPutALARm12SOURce @chlist

3Operating 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" on page 88.

•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.

	Digital Input Channel Numbering	Totalizer Channel Numbering
L4450A	1101 through 1104	1301, 1302
	1201 through 1204
L4452A	1001 through 1004	1005

•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[12]:SOURce (@<ch_list>)

To configure alarms on the specified digital input channel, use the following commands (also see the example below).

CALCulate

:COMPare:TYPE {EQUalNEQual},(@<ch_list>) :COMPare:DATA <data>,(@<ch_list>) :COMPare:MASK <mask>,(@<ch_list>)

Select EQUal to generate an alarm when the data read from the port is equal to CALC:COMP:DATA after being masked by CALC:COMP:MASK. Select NEQual (not equal) to generate an alarm when the data read from the port is not equal to CALC:COMP:DATA after being masked by CALC:COMP:MASK.

86 L4400 User’s Guide