Allen-Bradley Compact I/O 1769-ADN DeviceNet, User Manual

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Publication 1769-UM001B-EN-P - October 2002
How Communication Takes Place and I/O Image Table Mapping 2-19
1769-IF4XOF2 Combination
Analog Module
Input Data
The input data file provides access to input data for use in the control
program, over-range indication for the input and output channels, and
output data feedback as described below.
IMPORTANT
Input words 6 and 7 contain the Output Data
Echo/Loopback information for output channels 0
and 1 respectively. Bits 0 through 6 and bit 15 or
words 6 and 7 should always be set to zero in your
control program. If they are not set to 0, the invalid
data flag (Ex) will be set for that channel by the
module. However, the channel will continue to
operate with the previously converted value.
Wo
rd
Bit Position
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0 SGN Analog Input Data Channel 0 0 0 0 0 0 0 0
1 SGN Analog Input Data Channel 1 0 0 0 0 0 0 0
2 SGN Analog Input Data Channel 2 0 0 0 0 0 0 0
3 SGN Analog Input Data Channel 3 0 0 0 0 0 0 0
4 Not Used 1 I3 I2 I1 I0
5 Not
Used
H0 Not
Used
H1 Not Used
1
E1 E0 O1 O0
6 SGN Output Data Echo/Loopback for Output Channel 0 0 0 0 0 0 0 0
7 SGN Output Data Echo/Loopback for Output Channel 1 0 0 0 0 0 0 0
1 All unused bits are set to 0 by the module.
SGN = Sign bit in two’s complement format. Always positive (equal to zero) for the 1769-IF4XOF2 module.
Ix = Over-range flag bits for input channels 0 through 3. These bits can be used in the control program for error
detection. When set to 1, the bits signal that the input signal is outside the normal operating range. However, the
module continues to convert analog data to the maximum full-range value. When the over-range condition is cleared,
the bits are automatically reset (0).
Ox = Word 5, bits 0 and 1, provide over-range indication for output channels 0 and 1. These bits can be used in the
control program for error detection. When set to 1, the bits signal that the output signal is outside the normal
operating range. However, the module continues to convert analog data to the maximum full-range value. When the
over-range condition is cleared, the bits are automatically reset (0).
Under-range indication is not provided
because zero is a valid number.
Ex = When set (1), this bit indicates that invalid data (e.g. the value sent by the controller is outside the standard
output range or increment; e.g. 128, 256, etc.) has been set in the output data bits 0 through 6, or the sign bit (15).
Hx = Hold Last State bits. When set (1), these bits indicate that the channel is in a Hold Last State condition.
Words 6 and 7 = These words reflect the analog output data echo of the analog value being converted by the
digital/analog converter, not necessarily the electrical state of the output terminals. They do not reflect shorted or
open outputs.
It is only important to use the loopback function of input words 6 and 7 if the controller supports the
Program Mode or Fault Mode functions, and if it is configured to use them.
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