Rockwell Automation Publication 1769-UM021I-EN-P - May 2018 201
Use I/O Modules with CompactLogix 5370 L2 Controllers Chapter 8
When you enable open circuit detection for an input channel, an extra update
time is used to calculate the overall channel type. The increase in channel
update time is 11 ms for each channel that enables open circuit detection
response.
Tab le 16
lists example module update times that are based on channel
configurations.
Table 16 - Example Module Update Times
Example Enabled Analog Input
Channel Configuration
Channel Update Time Calculations Module
Update
Time
• Channel 0:
–Input type = Current
– Filter Frequency Selection = 60 Hz
57 ms 57 ms
• Channel 0:
–Input type = Current
– Filter Frequency Selection = 60 Hz
• Channel 2:
–Input type = RTD
– Filter Frequency Selection = 60 Hz
Channel 0 update time + Channel 2 update time
57 ms + 114 ms
171 ms
• Channel 0:
–Input type = Voltage
– Filter Frequency Selection = 60 Hz
– Open Circuit Detection = Enabled
• Channel 2:
–Input type = RTD
– Filter Frequency Selection = 10 Hz
(Channel 0 update time + Open Circuit Detection
time) + Channel 2 update time
(57 ms + 11 ms) + 614 ms
682 ms
• Channel 0:
–Input type = RTD
– Filter Frequency Selection = 10 Hz
– Open Circuit Detection = Enabled
• Channel 2:
– Input type = Thermocouple
– Filter Frequency Selection = 60 Hz
–CJC = Enabled
– Open Circuit Detection = Enabled
• Channel 3:
– Input type = Thermocouple
– Filter Frequency Selection = 500 Hz
–CJC = Enabled
– Open Circuit Detection = Enabled
(Channel 0 update time + Open Circuit Detection
time) + (Channel 2 update time + Open Circuit
Detection time) + (Channel 3 update time + Open
Circuit Detection time) + CJC Update time
(614 ms + 11 ms) + (57 ms + 11 ms)
+ (13 ms + 11 ms) + 114 ms
(1)
(1) If you select multiple thermocouples for your system, use the largest CJC Update time for your calculations.
831 ms
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