Fluke NetDAQ 2645A - Manual (Page 24)

2640A/2645A NetDAQ
Users Manual
1-8
Alarms 1-7.
Two alarms, Alarm 1 and Alarm 2, can be applied to any configured channel. An
alarm condition occurs when a measurement falls below a low alarm value or
rises above a high alarm value. You can use alarms to trigger scanning (see
“Alarm Triggering”) and to set a Digital I/O line to a logic low (see “Digital I/O”
below). NetDAQ Logger displays and records alarm conditions.
If you apply Mx+B scaling as part of the channel configuration, the instrument
bases the alarms on the scaled values. When any configured channel is in alarm,
the ALARM annunciator is on dim, or bright if a channel in alarm is being used as
an Alarm Trigger. When a channel is in alarm, the rear-panel Master Alarm
output is asserted (logic low). NetDAQ Logger displays and records alarm
conditions.
Channel Monitoring 1-8.
Channel monitoring takes place at the front panel of the instrument. Use the front
panel MON key and arrow keys to select a channel for monitoring. NetDAQ
Logger also allows the selection of a channel to monitor during scanning. For an
example of a front panel display of the instrument during monitoring, see Figure
1-3. The channel monitoring display updates once per second (nominal).
Digital I/O 1-9.
Eight general-purpose open-collector Transistor-Transistor Logic (TTL) digital
input/output (I/O) lines are available at the instrument rear-panel DIGITAL I/O
connector, terminals 7 through 0 (Figure 1-4). A logic low externally applied to an
I/O line is an input; a logic low internally set by the instrument is an output. An
output logic low condition takes precedence over an input logic high condition.
When the I/O lines are used as inputs, they signal an external condition that can
be correlated to the data measurements.
NetDAQ Logger displays and records the status of the Digital I/O as the decimal
equivalent of the eight binary bits. For example, 11111111 (DIO7 to DIO0) is
represented by decimal 255; 00001111 is represented by decimal 15.
The instrument can display the Digital I/O status in binary format at the front
panel with updates each second.
Totalizer 1-10.
The totalizer input counts contact closures or voltage transitions with a maximum
count of 4,294,967,295. The connections for the totalizer input line are at the
instrument rear panel DIGITAL I/O connector, terminals
Σ
and GND (Figure 1-
4). The instrument continuously detects the totalizer input on the rear panel
independently from instrument scanning and other activities. If the Totalizer