222 Rockwell Automation Publication 1715-UM001J-EN-P - December 2020
Chapter 8 Using SIL 2 Add-On Instructions with 1715 Redundant I/O Modules
An additional Add-On Instruction called CRC_calculator is automatically
imported when any of the Add-On Instructions that are listed previously are
imported. The CRC_calculator instruction calculates the CRC for incoming
packets and compares the result against the actual CRC received in the packet.
The instruction also calculates the CRC that is placed in the outgoing packet.
SIL 2 check data is added to data packets by the producer and the consumer
verifies this check data to determine the validity of the data transfer.
For input data from the 1715 modules, the 1715-AENTR adapter is the producer
and the ControlLogix controller is the consumer. The 1715-AENTR adapter
adds the check data, and the Add-On Instructions verify that valid data is
received within the connection reaction time limit (CRTL) of the module. If
valid data is not received within the CRTL, the instruction substitutes the
configured safe state values of the module in place of the invalid data.
For output data to the 1715 modules, the ControlLogix controller is the
producer and the 1715-AENTR adapter is the consumer. The Add-On
Instructions add SIL 2 diagnostic information (check data) to the module
assemblies, including a sequence number, source and destination IDs, and
CRC. The 1715-AENTR adapter verifies that valid data is received within the
CRTL. Outputs are placed into the safe state if the CRTL expires.
The 1715 input modules send data only in one direction, from the 1715-AENTR
adapter to the ControlLogix controller. In contrast, for the 1715 output
modules, data is sent in both directions (status to the controller and output
data from the controller).
The Add-On Instructions perform error rate monitoring on the input data they
process to verify that the maximum allowed error rate for SIL 2 has not been
exceeded. The error rate monitoring is performed automatically, requires no
1715-OB8DE
Simplex OB8DE_Simplex_SIL2
OB8DE_Simplex_SIL2_V3
Duplex OB8DE_Duplex_SIL2
OB8DE_Duplex_SIL2_V3
1715-IF16
Simplex IF16_Simplex_SIL2
IF16_Simplex_SIL2_V3
Simplex with HART IF16_Simplex_HART_SIL2_V3
Duplex IF16_Duplex_SIL2
IF16_Duplex_SIL2_V3
Duplex with HART IF16_Duplex_HART_SIL2_V3
1715-OF8I
Simplex OF8I_Simplex_SIL2
OF8I_Simplex_SIL2_V3
Simplex with HART OF8I_Simplex_HART_SIL2_V3
Duplex OF8I_Duplex_SIL2
OF8I_Duplex_SIL2_V3
Duplex with HART OF8I_Duplex_HART_SIL2_V3
1715-AENTR Duplex AENTR_SIL2
AENTR_SIL2_V3
Table 40 - SIL 2 Add-On Instructions
Module System Configuration Add-On Instruction Name
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