Rockwell Automation 1769-IF4XOF2 Compact 8-Bit Low Resolution Analog I/O Combination Module - Manual (Page 49)

Publication 1769-UM008A-EN-P - November 2001
1769-IF4XOF2 Module Data, Status, and Configuration Channels 4-5
Invalid Data Set (Ex)
Word 5, bits 2 and 3 provide invalid output data indication for output
channels 0 and 1, respectively. When either invalid output data bit is
set to 1, it indicates that invalid output data has been sent by the
controller to that channel of the module. When this occurs, the
module sets the appropriate (Ex) flag and continues to operate with
the previously accepted data.
NOTE: Invalid data is a value outside the standard range or increment.
For example, 128, 256, etc. or by writing to bits 0 though 6 and bit 15.
Hold Last State (Hx)
Word 5, bits 12 and 14, indicates that the channel is in a hold last state
condition when set to 1.
Analog Output Loopback/Data Echo
Input words 6 and 7, bits 7-14, 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.
IMPORTANT
Not all controllers support Hold Last State
functionality. Refer to your controller’s user manual.
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 of
words 6 and 7 should always be set to zero in your
control program, or the module will set the Invalid
Data Set (Ex) flag.
IMPORTANT
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.