Rockwell Automation 1715-OF8I Redundant I/O System User Manual - Manual (Page 227)

Rockwell Automation Publication 1715-UM001C-EN-P - March 2014 227
Using SIL 2 Add-On Instructions with 1715 Redundant I/O Modules Chapter 7
SIL 2 Check Data The instructions gather data from the module-defined configuration tags for the
following check data values .
The instructions add or check data for these fields.
Add-On Instruction Inputs The Add-On Instructions use these inputs.
Table 42 - 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 43 - 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 currently providing the safe state values, not valid application
data to the output modules. A reset is needed to begin providing valid application
data.
Table 44 - 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.