Rockwell Automation 1771-IFF/A,D17716.5.116 FAST ANALOG INPUT MODULE - Manual (Page 64)

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Publication 1771Ć6.5.116 - May 1996
When a BTR length of 0 is programmed, the 1771-IFF/A will
respond with the 1771-IFE series A module default length of 20.
The bit/word description for the block transfer read of the fast analog
input module is described below.
Table 12.A
BTR Word Format for the Fast Analog Input Module
Word Decimal Bit
(Octal Bit)
Description
Word 1
Bit 00
Power up bit (PU) - Used by the module to tell the processor that it is
alive but not yet configured. It is a key element in the application
program.
Bit 01
Out of range bit (OR) - This bit is sent to tell the processor that one
or more channels are either over or under range. 1
Bit 02
Invalid scaling bit (IS) - This bit reports that the scaling is somehow
invalid. Usually, both values are equal or minimum is greater than
maximum when this bit comes on. Can also be an invalid filter value.
Bit 03
Real time sample fault bit (RTS) - This bit is set if the module is
configured for RTS and a block transfer read has not occurred within
the user-programmed period.
Bit 04
Calibration status bit (CS) - When calibrating the module, this bit will
be cleared if the calibration was successful. If the bit is set, an
incorrect voltage/current was applied, or offset and gain calibrations
were attempted simultaneously.
Bit 05
EEPROM status bit (EE) - This bit is set if an error occurs saving
calibration data to nonvolatile memory. If this bit is set at powerup, the
data from the EEPROM did not pass the checksum and no calibration
values are used.
Bit 06
Hardware fault (HF) - When this bit is set, the dc/dc converter fuse
has blown. Digital logic will continue to operate.
Bits 07-15
(07-17)
Not used.
Word 2
Bits 00-15
(00-17)
Underrange bits for each channel. Bit 00 for channel 1, bit 01 for
channel 2, etc. 1 These bits are set (1) at approximately the input
range limits selected from Table 12.B.
Word 3
Bits 00-15
(00-17)
Overrange bits for each channel. Bit 00 for channel 1, bit 01 for
channel 2, etc. These bits are set (1) at approximately the input range
limits selected from Table 12.B.
Word 4 Bits 00-15
(00-17)
Polarity bits - Set when input is less than zero. Bit 00 for channel 1,
bit 01 for channel 2, etc.
Word 5 thru 20 Input values - Word 5 for channel 1, word 6 for channel 2, etc.
Word 21 Bits 00-15
(00-17)
Offset calibration results bits - Each bit represents a channel. After
a calibration BTW has been sent, the module confirms calibration by
echoing back the channels that were calibrated during the offset
calibration BTW. In differential mode, channels 09 thru 16 are zero.
Block Transfer Read
Format