Rockwell Automation Publication 1715-UM001J-EN-P - December 2020
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Chapter 8 Using SIL 2 Add-On Instructions with 1715 Redundant I/O Modules
The instructions add or check data for these fields.
Add-On Instruction Inputs
The Add-On Instructions use these inputs.
Table 41 - Check Data Values
Value
Description
VariantID
This is the revision of the module, which is always 2.
SourceIP
For input assemblies, this is the IP address of the 1715 adapter.
For output assemblies, this is the IP address of the ControlLogix Ethernet
module.
DestinationIP
For input assemblies, this is the IP address of the ControlLogix Ethernet
module.
For output assemblies, this is the IP address of the 1715 adapter.
SourceSlot
For input assemblies, this is the slot number of the 1715 module.
For output assemblies, this is the slot number of the ControlLogix controller.
DestinationSlot
For input assemblies, this is the slot number of the ControlLogix controller.
For output assemblies, this is the slot number of the 1715 module.
Table 42 - Add or Check Data Fields
Value
Description
SequenceNumber
The instruction monitors a sequence number in the module-defined Input
Data tag. In normal operation, the sequence number increments by 1 with
each incoming packet:
• If the sequence number is a duplicate or is lower than expected, data is
discarded as invalid. The CRTL is not reset.
• If the sequence number is higher than expected but within a deadband of
100, the data packet is accepted. Data remains valid and the CRTL is reset.
• If the sequence number is more than 100 greater than the expected
number, the data is discarded as invalid. The CRTL is not reset.
For each output packet, the instruction increments the sequence number,
starting with 0 when the connection is initially established.
Important: The sequence number is not configurable.
CRC
The instruction calculates a CRC on the input data based on the module-
defined input tag and compares this value against the CRC in the input data. If
the CRCs do not match, the data is discarded as invalid.
The instruction calculates a CRC on the output data based on the complete
module-defined output tag. This CRC is added to the 1715 module-defined
output tag.
SIL2ResetNeeded
(output modules only)
After the CRTL expires, the 1715-AENTR adapter adds this flag to the SIL 2
check data to indicate that it is providing the safe state values, not valid
application data to the output modules. A reset is necessary begin providing
valid application data.
Table 43 - Add-On Instruction Inputs
Input
Description
Config_Data
The Add-On Instruction gets the appropriate SIL 2 check data values from
this module-defined configuration tag. The instruction uses this check data
to populate the 1715 output data and verify the 1715 input data. You must point
to this tag when configuring the Add-On Instruction.
Requested_Output_Data
Only for output modules: This user-defined Requested Output Data tag
contains data from the program logic. The output Add-On Instruction takes
this requested output data, adds the check data, and places this data in the
module -defined Output Data tag.
Output_Data
This is the raw data sent to the 1715 module. You must point to this tag when
configuring the Add-On Instruction.
Reconciled_Input_Data
If the Add-On Instruction examines the check data and determines that the
input data is valid, the data in this tag is a duplicate of the original data that
is received from the input module.
If the Add-On Instruction examines the check data and determines that the
data is not valid, the safe state values are substituted in the Reconciled Input
Data tag.
This is the input data to be used in the logic program.