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2640A/2645A NetDAQ
Users Manual
2-24
Displaying the Digital I/O Status 2-28.
Perform the procedure in Figure 2-14 to display an instrument Digital I/O line
status. The instrument updates the DIO display once per second. (See Figure 2-15
for examples.)
• Number Of DIO Lines There are eight DIO lines: DIO 0 to DIO 7. You can
assign DIO lines as alarm outputs or as digital inputs. For example, a switch
closure can toggle a DIO line as an input.
• DIO Status Display DIO status display is in the form nnnn-nnnn with five
characters in view at a time.
DIO
Press the DIO (Digital I/O) key to view the Digital I/O status. You can display the
Digital I/O status whether the instrument is scanning or not scanning.
Press the left/right arrow keys to display the desired DIO line, DIO7 to DIO0.
A hyphen divides the display, for example, 1111-0000.
DIO
Press the DIO key again to exit. NetDAQ Logger for Windows can also display
the Digital I/O status.
Figure 2-14. Displaying the Digital I/O Status
Input example Toggling DIO7 between open circuit and ground results in I/O
status of 255 (11111111) and 127 (01111111). The changes from 255 to 127 in
your scan data provide a direct correlation between the external condition at DIO7
and the analog and computed measurements.
Output example Associating I/O line DIO0 with an alarm results in I/O status of
255 (11111111) when the channel is not in alarm and 254 (11111110) when the
channel is in alarm. External equipment such as warning lights can process the
logic low output on the Digital I/O connector.
Associating an I/O line with an alarm condition is part of the alarm’s
configuration procedure. (See “Alarms” in Chapter 3 of this manual.)