example of using a teco L510 VFD with an esp32.
This uses UART1 of the esp32 via pins 16 and 17. The RS485 module is the HW-0519 with automagic rx/tx enable.
To control the VFD:
CR/LF control the commands, ensure you have it set in your serial program Start "+" Stop "-" Frequency "F XXXXX" where XXXXX is the frequency * 100 aka 10000 == 100hz