Module i/o functions – Rockwell Automation 5370-CVIM2 Module User Manual
Page 467
Chapter 9
Discrete I/O Assignments
9–4
Hardware Interrupt
When a trigger is assigned to either input line on the
Module I/O
panel, or to
any of lines 0 through 3 on the
System I/O
panel, the CVIM2 system will
automatically process triggers using hardware interrupts. When a trigger
occurs, the CVIM2 system hardware responds immediately and diverts the
software operation to starting an inspection cycle. The system response time
to a hardware interrupt is in the microsecond range.
Note that triggers can be assigned to lines 4 through 15 on the
System I/O
panel; however, the system will use the polling method to process triggers on
those lines. Since polling has a resolution in the millisecond range, it may be
too slow to process triggers; and, when trigger pulses are of short duration,
the system may miss some of those triggers.
Polling
When an input other than a trigger is assigned to any of the input lines, the
CVIM2 system will use polling to process the input, regardless of whether
the line is capable of performing hardware interrupt processing. When using
polling, the system software checks the state of the input line periodically (at
approximately 25ms intervals), and performs the appropriate operations
when is detects a change of state on the input line.
When the
Module I/O
format is on the monitor screen (see Figure 9.1, page
9–1), the top two rows of the table are dedicated to discrete input signal
assignments, while the 14 remaining rows are dedicated to discrete output
signal assignments. The inputs and outputs assigned in this panel are routed
to the
Module I/O
connector on the CVIM2 front panel.
Trigger Input Selections
As noted above, the first two discrete I/O locations are reserved for inputs
only. To assign a trigger source to either input, pick the corresponding box
under the
Signal Name
heading. When you do, the
Input Signals
menu
appears, as shown in the example in Figure 9.2 (page 9–5).
Note that only the trigger names that are defined in the currently selected
configuration file will appear in the
Input Signals
menu at this time. Since
most inspection applications must be synchronized with external events, such
as a sensor activated by parts or assemblies moving down a conveyor belt, a
trigger signal will normally be routed from such an external source.
Module I/O Functions