Rockwell Automation Publication 1769-IN088A-EN-P - February 2011 105
I/O Memory Mapping Chapter 3
• OCx = Open-circuit detection bits indicate an open input circuit on
channels 0…5 (OC0…OC5) and on CJC sensors CJC0 (OC6) and CJC1
(OC7). The bit is set (1) when an open-circuit condition exists.
• Ux = Under-range flag bits for channels 0…5 and the CJC sensors (U6 and
U7). For thermocouple inputs, the under-range bit is set (1) when a
temperature measurement is below the normal operating range for a given
thermocouple type. For millivolt inputs, the under-range bit indicates a
voltage that is below the normal operating range. These bits can be used in
the control program for error detection. The bits are reset (0) by the
module when within the normal operating range.
• Ox = Over-range flag bits for channels 0…5 and the CJC sensors (O6 and
O7). For thermocouple inputs, the over-range bit is set (1) when a
temperature measurement is above the normal operating range for a given
thermocouple type. For millivolt inputs, the over-range bit indicates a
voltage that is above the normal operating range. These bits can be used in
the control program for error detection.
Configuration Data File
During initial system configuration, you normally manipulate the bits from the
configuration data file with programming software, such as RSLogix 500,
RSLogix 5000, or RSNetWorx for DeviceNet. Graphical screens simplify
configuration. However, some products, like the 1769-ADN DeviceNet adapter,
also let you alter the bits as part of the control program, by using communication
rungs. In this case, you need to understand the bit arrangement. Refer to the
Compact Thermocouple/mV Input Module User Manual, publication 1769-
UM004, for additional details.
Words 0…5 of the configuration data file let you change the parameters of each
channel independently. For example, word 0 corresponds to channel 0. See the
functional arrangement of the bits for a single word/channel in the
Configuration Data File
on page 106.
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