Rockwell Automation 1771-IL/B , D17716.5.91 ISOLATED ANALOG INPUT Module User Manual
Page 39
Module Status and Input Data
Chapter 5
5-2
The Isolated Analog Input Module (1771-IL series B) reports the status of
all eight channels to the processor as outlined below.
Table 5.A
Bit/Word Descriptions for the Isolated Analog Input Modules (1771-IL)
Read Block Transfer Data
Word
Decimal Bit
(Octal Bit)
Description
Bit 00
Power up bit (PU) is set after initial power up. It will not reset until the
module receives a valid write block transfer.
Note: Input data is set to zero until the first BTW is received.
Bit 01
Out of range bit (OR) is set if one or more channels are either over or
under range.
Bit 02
Invalid scaling bit (IS) is set if the firmware cannot use the scaling
data in the BTW. Acceptable values are between -9999 and +9999 in
BCD, and -32767 to +32767 in binary.
1
Bit 03
Real time sample (RTS) time out bit is set if the module is using RTS
and a block transfer read has not occurred within the programmed
RTS period.
Word 1
Bit 04
Invalid Filter bit (IF) is set if the filter parameters are not correct. The
value must be between 00 and 99 (0.00 and 0.99 seconds) in
BCD; or 0 and 255 (0 to 2.55) in binary.
Bit 05
Invalid Alarm bit (IA) is set if any alarm value is unusable, such as
expecting BCD and value is in 2’s complement binary.
Bit 06
Hardware Failure bit (HF) is set if the analog module has an internal
hardware failure (such as fuse blown or open, etc.).
Bit 07
Alarm violation status bit (A) is set if one or more channels are in an
alarm condition.
Bits 08-15
(10-17)
Not used
2
Bits 00-07
Individual underrange bits for each channel. Bit 00 for channel 1, bit
01 for channel 2, etc.
Word 2
Bits 08-15
(10-17)
Not used
3
Bits 00-07
Individual overrange bits for each channel. Bit 00 for channel 1, bit
01 for channel 2, etc.
Word 3
Bits 08-15
(10-17)
Not used
Word 4
Bits 00-07
Polarity (sign) bits are set when the input is less than zero in both
BCD and signed magnitude data formats. Bit 00 for channel 1, bit 01
for channel 2, etc.
Word 4
Bits 08-15
(10-17)
Not used
Word 5 thru 12
Input data values. Word 5 for channel 1, word 6 for channel 2, etc.