This manual will provide instructions on how to connect your Rockwell Ethernet I/P capable PLC to a network of ConveyLinx modules. There are three basic methods for connecting ConveyLinx to Rockwell PLCs:
- Use Generic Ethernet Device
- Import EDS and optionally import and use AOIs
- Use MSG Instruction
All three methods can be used for ConveyLinx modules in ZPA mode and in PLC I/O mode. However, the MSG Instruction method does not maintain a constant connection to a ConveyLinx module and should not be used for “time critical” operations.
Ethernet I/P Guidelines
Each Allen-Bradley PLC has 2 metrics for limiting maintained Ethernet I/P communications to remote devices:
- Fixed quantity of TCP connections available on its Ethernet Port
- Fixed quantity of I/O data table memory available for connected devices
If the limit of either of these quantities is reached, the PLC processor will indicate I/O communications fault on one or more instances of device declaration. For ConveyLinx device declarations utilizing either ZPA or PLC I/O Mode instances, in general the PLC limitation on TCP connections will be reached before I/O data table memory limit is realized.
For example, for a CompactLogix L3x series processor, the documented quantity of TCP connections available on its Ethernet Port is 32. The processor always keeps one TCP connection in reserve for programming terminal access, etc. An L3x series processor can accept 31 full-time ConveyLinx Connections as generic I/O modules utilizing any combination of ZPA mode and PLC I/O Mode instances.
When a ConveyLinx module is attached as a “full-time generic I/O module” to the PLC, the connection is continually maintained and data is exchanged at a minimum RPI value (referred to as an implicit connection). If the PLC cannot communicate with the ConveyLinx module for any reason, the PLC’s I/O tree will register a fault. It is possible for the PLC to communicate via Ethernet I/P with any ConveyLinx module it can physically reach over its Ethernet port without the module being “full-time connected as a generic I/O module”. This is accomplished with a Logix5000 MSG instruction (referred to as explicit connection).