I'm new to this and I feel like I'm missing a fundamental piece of knowledge that's preventing me to fully understand how this should work. I can't contact vendors or anything like that for support, yet, but finding an answer to these questions (and possibly to what's wrong with my understanding) might require expertise.

What I know:

1. EtherCAT is a protocol which uses Ethernet frame as its "envelope"
2. It's a master slave architecture, with the EtherCAT master sending a PDU to the next device, forwarded downstream by every device along the way
3. Each device processes the PDU on the fly, reading and writing to it as it passes by
4. Each device knows what data is addressed to it by using either FMMU, mailboxes... configured with some tool using their respective ESI files

I tested this using CODESYS with which I simulated an EtherCAT master PLC, with a demo version of EtherCAT slave provided by TI AM243x. The default PDO mapping of the slave's ESI file allowed me to read the states of some LEDs from the first object in its TPDO, and control their state (light on/off) through the first object in its RPDO.

So the way I understand this is: each device has a list of objects it can expose on the network through its ESI file. The list itself is an object dictionary. Each object has its index/subindex. Some of them can be mapped to RPDO/TPDO. It's up to some guy to configure the network through the EtherCAT master to make the mapping they want (e.g. I want device A to write signal indexB/subindexB of device B through RPDO).Please correct if something's wrong.

Now it gets harder. My AM243x will run a PLC-like application, and will expose some input and output signals to be received over the network. So basically I want to give the possibility to other devices to send me some signals and to receive some signals from me, but the data is safety related. So I will integrate an FSoE stack to allow my device to be in an FSoE connection. An FSoE connection is basically about making two devices exchange safety data over the EtherCAT network which is by design, not safe. It's about setting one device which will act as FSoE master, another one as FSoE slave, and setting some stuff for them to exchange safety data (device addresses, connection ID, watchdog time...).

• Can an FSoE connection between 2 devices be fully configured with a tool, or should part of it be hardcoded in my AM243x?
• Exactly what setting can and must be configured through a tool?
• Can the tool to configure the EtherCAT network be the same one used for configuring the FSoE connections?
• Can I just provide my device with an object dictionary to other people's network and tell them they can setup an FSoE connection and write/read the signals I can offer, all just thanks to my ESI file + EtherCAT + FSoE stack?

I see all sorts of things on how to configure an FSoE connection.