Rockwell Automation Publication 1715-UM001J-EN-P - December 2020 237
Chapter 8 Using SIL 2 Add-On Instructions with 1715 Redundant I/O Modules
If you are not using COS, the worst-case reaction time from input screw
terminal to output screw terminal is equal to 210 ms plus the following:
- Input RPI
- Output RPI
- Add-On Instruction Module RPI/2
- SIL 2 Task Period x 2
- SIL 2 Task Watchdog x 2
If you are using COS, the worst-case reaction time from input screw terminal
to output screw terminal is equal to 270 ms plus the following:
- Output RPI
- Add-On Instruction Module RPI/2
- SIL 2 Task Period x 2
- SIL 2 Task Watchdog x 2
Using the Add-On
Instruction Data Tags in an
Application Program
The following illustrations provide basic examples of how the
Requested_Output_Data tag and the Reconciled_Input_Data tag could be used
in program logic. Data is written to the requested output and read from the
reconciled input, while the raw data in the module-defined input and output
tags is ignored.
Table 48 - Worst Case Reaction Time Calculations
Worst Case Factors Value
Fixed Time
(ms)
User
Configurable
Time (ms)
Description
1715 Input Module Delay 15
1715 Backplane Rate 65
1715-AENTR Delay 25
Input Data to ControlLogix
COS=NO 1715 Input Module RPI 60 COS = Change of State
COS=YES Fixed 60
Add-On Instruction Module RPI AOI Module RPI/2 30 Value that is entered into the AOI Module_RPI parameter
ControlLogix SIL2 Task
Watchdog
SIL 2 Task Watchdog 20
ControlLogix system runs input module AOI and controls
requested output
Assumes requested output in same SIL 2 task as 1715 SIL 2 AOIs
Add-On Instruction Module RPI AOI Module RPI/2 30 Value that is entered into the AOI Module_RPI parameter
ControlLogix SIL2 Task
Watchdog
SIL 2 Task Watchdog 20
ControlLogix system runs output module Add-On Instruction and
places requested outputs in output module raw data
Output Data to 1715-AENTR 1715 Output Module RPI 80
1715-AENTR Delay 25
1715 Backplane Rate 65
1715 Output Module Delay 15
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