In the standard setup at PSI over current protection modules are used to feed 24V to both the EtherCAT communication bus (E-bus) and the power bus of the EtherCAT slaves. If the over current protection is not enabled then the EtherCAT slaves will not receive power.
First time, (and only first time), a system is in use, the over-current modules needs to be enabled in order to allow current to flow. Enabling is done by push buttons in the LED area of the module. The long horizontal LEDs are in fact buttons that can be used to activate or tripp the over current protection.
Before pressing any button, check the electrical drawings and make sure it’s safe to power on the system.
The EL9221-5000 has one channel and therefore only the top button is needed to be pressed.
The EL9227-5500 is a 2 channel module and normally both channels needs to be enabled by pressing both the top and bottom long LED. if only one are pressed it could result in that the power to the communication is fine but the power to the i/o bus is lacking. This can result in strange issues. Both EL9227-5500 and EL9221-5000 have dedicated panels where status of the over current protection can be seen.
Some terminals are passive. Passive terminals are not EtherCAT slaves and do not communicate over EtherCAT (not equipped with EtherCAT slave controller). Passive terminals are normally used to simplify electrical connections (avoiding external terminals). For instance for distributing potential, 24V and 0V, an EL9184 can be used (8Ch 24V and 8Ch 0V).
The passive terminals will not show up as an EtherCAT slave when issuing the “ethercat slaves” command. However, they are normally visible in the electrical drawings. This could result in that the slave id in the electrical drawing is NOT corresponding to the EtherCAT slave index used when configuring ecmc. In worst case this could lead to that the wrong hardware/drive is configured.
When configuring ecmc, make sure the EtherCAT slave index is correct, do not blindly trust the electrical drawings since a passive terminal could introduce an shift in the slave indices.