modbus_write_bits - Man Page

write many bits


int modbus_write_bits(modbus_t *ctx, int addr, int nb, const uint8_t *src);


The modbus_write_bits() function shall write the status of the nb bits (coils) from src at the address addr of the remote device. The src array must contains bytes set to TRUE or FALSE.

The function uses the Modbus function code 0x0F (force multiple coils).

Return Value

The function shall return the number of written bits if successful. Otherwise it shall return -1 and set errno.



Writing too many bits

See Also

modbus_read_bits(3) modbus_write_bit(3)


The libmodbus documentation was written by Stéphane Raimbault <>

Referenced By

libmodbus(7), modbus_read_bits(3), modbus_write_bit(3).

07/20/2023 libmodbus v3.1.7 libmodbus Manual