All PLC communications assemblies for ConveyLinx modules include a reserved set of registers for ConveyStop command output and status input. Please refer to Appendix B – PLC Instance Usage for details on the particular PLC and instance connection you want to use.
Regardless of which network the PLC uses (Ethernet I/P, Modbus TCP, or Profinet), the data transfer between ConveyLinx modules (ERSC or CNIP) is organized in blocks of registers defined as Assembiles. Each Assembly is part of an input / output pair. The input assembly provides status input data to the PLC to read and the output assembly is used by the PLC to write data to the ConveyLinx module.
Within each Input Assembly is a ConveyStop Status Register and within each Output Assembly is a ConveyStop Command Register. Regardless of PLC, each register is a 16-bit value.
If a PLC establishes an Ethernet I/P assembly instance connection to at least one ERSC or CNIP module within a Stop Group, then the ConveyStop control within the Stop Group will expect this connection to always be present. If this connection is ever lost, then a Stop Condition is triggered for the Stop Group. If the PLC has established connections to multiple modules within a Stop Group; the loss of connection to any one of these connections will trigger a Stop Condition for the Stop Group.
Please Note: ERSC and CNIP modules will also respond to unsolicited MSG instruction requests from the PLC. This form of communication does not require the ERSC or CNIP to be configured as a “permanent” Ethernet module on the PLC’s logic Ethernet backplane. If the PLC establishes communication with an ERSC or CNIP within a Stop Group with a MSG instruction request; the ConveyStop control does not treat this as an expected connection and does not generate a Stop Condition for any MSG instruction communication presence or loss.
Modbus TCP is a request/response type protocol and each ERSC or CNIP module acts as a Modbus TCP server and will respond to holding register read/write requests. Holding Register addresses 4:1000 and above are reserved for assembly instances. If a PLC establishes communications to at least one module in a Stop Group to read/write to any block of holding registers at address 4:1000 or above and these read/write communication requests from the PLC is missing for more than 100 msec; a Stop Condition will be generated.
If a PLC establishes a connection to read/write to Holding Registers whose addresses are in the range of 4:0001 thru 4:999; a loss of connection for this communication will not result in a Stop Condition
Profinet I/O connection works similarly to Ethernet I/P with ConveyStop. If a PLC establishes a connection to one or more modules within a Stop Group; then the ConveyStop control within the Stop Group will expect all of these connections to always be present. If any one of these connections is lost, then a Stop Condition is triggered for the Stop Group