Rockwell Automation 1772-LP3 PLC - 2/30 Programmable Controller Programming and Operations Manual - Manual (Page 162)

Peripheral Functions
Chapter 8
8Ć3
Table 8.C
Contact Histogram Functions
Function Mode Key Sequence Description
Contact Histogram
Continuous
RUN
RUN/PROGRAM
or TEST
[SEARCH] [6]
[Bit Address]
[DISPLAY]
[CANCEL COMMAND]
Provides a continuous display of the ON/OFF history of the
addressed bit in hours, minutes, and seconds.
Can obtain a hardcopy printout of contact histogram by
connecting a peripheral device to Channel C and selecting
proper baud rate before indicated key sequence.
To terminate.
Contact Histogram Paged RUN
RUN/PROGRAM
or TEST
[SEARCH] [7]
[Bit Address]
[DISPLAY]
[DISPLAY]
[CANCEL COMMAND]
Displays 11 lines of the ON/OFF history of the addressed
bit in hours, minutes, and seconds.
Displays the next 11 lines of contact histogram.
Can obtain a hard copy printout of contact histogram by
connecting peripheral device to Channel C and selecting
proper baud rate.
To terminate.
After pressing [DISPLAY], the data of the histogram will be displayed on
every other line with 5 frames of data per line. Each frame of data contains
the on or off status and the length of time in hours, minutes and seconds
[read between the dash (–) symbols] in the format shown in Figure 8.1.
Figure 8.1
Contact Histogram Display
On Time Off Time On Time
hr. mn. sec.
If the bit is changing states faster than can be printed or displayed, a buffer
is maintained to store these changes. If the buffer becomes full, all
monitoring stops and a BUFFER FULL message will be displayed.
Subsequent changes in the on-off status of the device are lost until the
histogram function finishes printing out or displaying the data in the buffer.
Then a BUFFER RESET message will be displayed and the histogram
function will resume.