modbus_read_input_bits - Man Page

read many input bits


int modbus_read_input_bits(modbus_t *ctx, int addr, int nb, uint8_t *dest);


The modbus_read_input_bits() function shall read the content of the nb input bits to the address addr of the remote device. The result of reading is stored in dest array as unsigned bytes (8 bits) set to TRUE or FALSE.

You must take care to allocate enough memory to store the results in dest (at least nb * sizeof(uint8_t)).

The function uses the Modbus function code 0x02 (read input status).

Return Value

The function shall return the number of read input status if successful. Otherwise it shall return -1 and set errno.



Too many discrete inputs requested

See Also



The libmodbus documentation was written by Stéphane Raimbault <>

Referenced By

libmodbus(7), modbus_read_input_registers(3).

01/25/2024 libmodbus v3.1.7 libmodbus Manual