modbus_write_and_read_registers - write and read many registers in a single transaction
The modbus_write_and_read_registers() function shall write the content of the
write_nb holding registers from the array 'src' to the address
the remote device then shall read the content of the
read_nb holding registers
to the address
read_addr of the remote device. The result of reading is stored
dest array as word values (16 bits).
You must take care to allocate enough memory to store the results in
nb * sizeof(uint16_t)).
The function uses the Modbus function code 0x17 (write/read registers).
The function shall return the number of read registers if successful. Otherwise it shall return -1 and set errno.
- EMBMDATA, too many registers requested, Too many registers to write