Thanks so much for the replies! I figured out the location last week. Could have saved myself a lot of sleuthing if I waited, but at least I know a bit more about how this library works. This is what I came up with.. Do I need to specify if is FLOAT or UINT32 ?? if (request.reg_size == 2 && reg_info...

Turns out I had a bad MAX485 transceiver causing the timeouts. I swapped it out and It now gets the data successfully but still in the wrong order (Little Endian on 32bit values).

I would appreciate any thoughts or success stories getting around this.

The [Modbus][https://docs.espressif.com/projects/esp-idf/en/latest/esp32/api-reference/protocols/modbus.html] Serial Master module works when accessing "Little Endian" slaves but fails with a timeout when accessing "Big Endian" slaves. I verified this with a modbus slave simulator on the desktop, ke...