In Node-red, drect firmata connection takes serial port (e.g. /dev/USB0) directly connected to arduino running firmata (57600).
Over TCP connection, it uses IP address and port.
Firmata starts with following string "StandardFirmata.ino" and then the data is binary.
The bridge seems to transport that string correctly, but no data exchange follows.
Is ESP-LINK TOTALLY transparent?
Problem was a baud issue - for some reason Firmata on node-red requires 115200, whereas normal is 57600.
Also, I couldn't get it to work using TCP connection from node-red, instead had to map a virtual tty using socat, and then use serial connection in node-red.
But whatever, it proves that esp-link is doing its thing correctly - transparent bridging.
Thankyou !!!!
Thanks for reporting back!