Rockwell Automation 1756-OF8I ControlLogix Eight-channel Isolated Analog I/O Modules - Manual (Page 70)

70 Rockwell Automation Publication 1756-UM540A-EN-P - May 2014
Chapter 4 1756-IRT8I Combined Temperature-sensing Isolated Analog Module
Underrange/Overrange Detection
This feature detects when a temperature-measuring input module is operating
beyond limits set by the input range. For example, if you are using the
1756-IRT8I module in the 2…1000
Ω
input range and the module resistance
increases to 1050
Ω
, the overrange detection detects this condition.
The table lists the input ranges of non-isolated input modules and the lowest/
highest signal available in each range before the module detects an underrange/
overrange condition.
To see where to set the Underrange/Overrange detection values, see page 131 .
Table 9 - Low and High Signal Limits on Temperature-measuring Input Modules
Input Type Available Range Underrange Threshold Overrange Threshold
RTD 1…500
Ω
< 0.00
Ω
510.00
Ω
2…1000
Ω
< 0.00
Ω
1020.00
Ω
4…2000
Ω
< 0.00
Ω
2040.00
Ω
8…4000
Ω
< 0.00
Ω
4080.00
Ω
Thermocouple -100…100 mV - 101.00 mV 101.00 mV
IMPORTANT Be aware that the Disable All Alarms feature, does not disable the
underrange/overrange detection feature. The Disable All Alarms feature
disables all alarms on the module.
The underrange/overrange detection feature is not an alarm. It is an
indicator that channel data has gone beyond the absolute maximum or
minimum, respectively, for the channel’s chosen range but does not trigger
an alarm.
To disable the underrange/overrange detection feature, you must disable
the channel.