Rockwell Automation 1771-IFE , D17716.5.90 USER MNL. ANALOG INPUT Module - Manual (Page 45)

Troubleshooting Your Input Module
Chapter 7
7-2
Word 1
Diagnostics word 1 is the first data word in the read block transfer file for
transfer to the central processor. It contains a power-up bit (bit 00) that is
set (1) when the module is first powered up. It is reset (0) after a write
block transfer. It also contains an under-range or over-range bit (bit 01)
that is set when any input is under or over-range.
An invalid scaling data bit (bit 02) will be set if invalid scaling data is
entered into any of the minimum/maximum scaling value words. Note that
minimum equal to maximum is an invalid value. If invalid values are
entered into the minimum or maximum scaling words the corresponding
read block transfer input channel word will be set to 0000.
Bit 02 will also be set if an invalid digital filter value is entered (e.g., 1F).
If an invalid digital filter value is entered, the module will not perform
digital filtering.
The real time sample (RTS) fault bit (bit 03) is set if the module is
configured for RTS and a block transfer read has not occurred within the
user-programmed period.
Word 2
Word 2 provides for under-range conditions. When a particular channel
input is under-range, the associated bit will be set. As long as inputs are
under range the associated bit will remain set. Bit 00 corresponds to
channel 1, bit 01 to channel 2, etc.
Word 3
Word 3 provides for over-range conditions. When a particular channel
input is over-range, the associated bit will be set. As long as inputs are in
range the associated bit will remain reset. Bit 00 corresponds to channel 1,
bit 01 to channel 2, etc.
Word 4
Word 4 provides an indication of a particular channel’s input polarity (set,
or 1 = negative; reset, or 0 = positive). Bit 00 corresponds to channel 1, bit
01 to channel 2, etc.
Table 7.A lists the probable cause and recommended actions for a number
of common trouble indications.