Fluke 2620A, 2625A user manual Resetting Alarm Conditions, Using the Digital I/O Lines

Operating the Instrument from the Front Panel	3
Channel Configuration

Alarm annunciation is disabled when the instrument is in Inactive or Configuration Mode.

ALARM annunciation and evaluation follow these rules:

1.When any channel reading from the latest scan is in alarm (but the presently displayed channel is not in alarm or a scan interval countdown is in progress):

"ALARM" annunciator is dimly lit.

2.If the presently displayed channel (i.e., the Monitor or the Review array Last channel) is in alarm:

"ALARM" annunciator flashes. Sand/or Tlimit annunciator on brightly. "HI" and/or "LO" sense annunciator on brightly. "LIMIT" annunciator on brightly.

3.If the present channel is in alarm with a value of "OL" displayed:

"OL" means that a very large positive number is used for alarm evaluation. "-OL" means that a very large negative number is used for alarm evaluation.

4.If the present channel shows a value of "otc":

Alarm limit checking is no longer occurring for that channel. Alarm status remains as it was prior to the "otc" condition.

5.If no channels are in alarm:

All alarm-related annunciators ("ALARM", S, T, "HI", "LO", "LIMIT") are off.

Note

Alarms encountered during scan measurement can generate a low level on an assigned output. If an alarm is encountered and just the monitor function is selected without the scan function, the front panel will indicate the alarm; but, the alarm output will not change to indicate the alarm. An IEEE-488.1 SRQ can also be generated when an alarm condition is set or cleared.

Resetting Alarm Conditions

When review values are cleared, all alarm status is also removed. This action occurs in the following instances:

∙A channel function is changed or set to OFF.

∙A channel range is changed.

∙CLEAR (KN) is selected while Review array data is being examined.

∙Configuration Reset occurs (power up Cor *RST)

Changing an alarm definition clears the alarm status for the changed alarm limit.

Using the Digital I/O Lines

The rear panel Digital I/O Connector provides eight lines (numbered 0 through 7) that are individually usable as inputs or outputs. No preconfiguring for the use of these lines is necessary; an input low signifies that the line is an input, and an output low signifies that the line is an output. Output low conditions take precedence over input low conditions.

Both alarm limits Sand Tfor channels 0 through 3 are permanently assigned to alarm outputs 0 through 3, respectively, on the rear panel Alarm Output Connector.

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