Feature Pack Hot Connect
Achieving a maximum flexibility with “Hot Connect”
The concept of “Hot Connect” first of all refers to the connecting and disconnecting of slaves in a running (hot) system.
However, this is just one of several possible scenarios.
Much more often it is required to operate the system without a perfect match between the EtherCAT bus configuration (ENI file) and the actually connected slaves or wiring.
Thus the following additional use cases can be covered (without the need to change the ENI configuration file):
- Setting up a complex control system, while parts of the system are not available, powered-off or disconnected.
- Running a system that consists of mandatory as well as optional devices (e.g. in a test & measurement environment)
- Flexibility within the wiring: slaves can be connected to different ports (e.g. analogue to CAN).
In order for “Hot Connect” to be used, no special EtherCAT functionality in the slave is required; in fact, any EtherCAT slave may be a member of a HotConnect group (HC group).
Every HC group just has to be uniquely identifiable, most often this is implemented using DIP switches.
This unique slave address then appears either in the Station Alias Register or at some address location within the slave memory.
Both methods are supported by the EtherCAT Master.
Furthermore, the application may program the station alias address by means of the master (e.g. for first-time system initialization).
The “Hot Connect” Feature Pack requires at least version 2.0 of the EC-Master stack.
All EtherCAT activities required to support HC are automatically handled by the stack in the background. There is no need for the application to interact.
Besides, as soon as a slave is connected or disconnected, the application will be informed by a call-back function (notification).
At any time the application may determine the actually connected slave devices using the appropriate master stack API function.
Within the HC feature pack the functionality “Border Close” offers additional security against connecting of slaves to an incorrect port.
By activating that function, all EtherCAT ports are closed, except the ports which are permitted by the configuration. Therefore slaves which are connected to these ports, are simply ignored and the system continues to run perfectly undisturbed.
We will be glad to answer any further questions concerning the topic “Hot Connect”.