Rockwell Automation 1769-IF16V Compact High Density Analog Input Modules - Manual (Page 44)

44 Publication 1769-UM018A-EN-P - October 2008
Chapter 3 Module Data, Status, and Channel Configuration
When time stamping is enabled, the module provides a rolling time
stamp value of 0…32,767 with each count representing 1 ms. When
the time stamp count reaches 32,767, the value is reset to 0 and
continues to increment one count every millisecond.
When enabled, the Input Data file is updated with the latest time
stamp value which corresponds to the end of each module conversion
cycle. Sequentially, each input pair, where at least one of the channels
is enabled, is converted once per conversion cycle. In normal
sampling mode, when Real Time Sampling is not enabled, conversion
cycles are repeatedly initiated at the module update rate. If Real Time
Sampling is used, the conversion cycles are initiated at a rate equal to
the real time sampling rate. The time stamp value is updated at the
end of every conversion cycle.
Process Alarms
Process alarms alert you when the module has exceeded configured
high or low limits for each channel. You can latch process alarms.
Process alarms can generate interrupts
(1)
. A channel’s process alarms
are set at two user configurable alarm trigger points:
•
Process Alarm High
•
Process Alarm Low
The operation of each input channel’s process alarms are controlled
by bits in the Configuration Data file. Enable alarms for a channel by
setting (1) the EA bit for that channel. Set the AL bit (1) for a channel
to enable the alarm latching. Set the EI bit (1) for a channel to enable
interrupts on that channel’s process alarms
(1)
.
Each channel’s process alarm high data value and process alarm low
data value are set by entering values in the corresponding words of
the Configuration Data file for that channel.
The values entered for a channel’s process alarms must be within the
full-scale data range as set by the input Data Format selected for that
channel. If a process alarm data value is entered that is outside the
full-scale data range set for a channel, the module indicates a
configuration error.
(1) Module interrupts are not supported by all bus masters. Refer to your controller’s user manual to determine
whether it can support module interrupts.