modbus_mask_write_register - Man Page

mask a single register


int modbus_mask_write_register(modbus_t *ctx, int addr, uint16_t and, uint16_t or);


The modbus_mask_write_register() function shall modify the value of the holding register at the address addr of the remote device using the algorithm:

new value = (current value AND 'and') OR ('or' AND (NOT 'and'))

The function uses the Modbus function code 0x16 (mask single register).

Return Value

The function shall return 1 if successful. Otherwise it shall return -1 and set errno.

See Also

modbus_read_registers(3) modbus_write_registers(3)


Martijn de Gouw <> The libmodbus documentation was written by Stéphane Raimbault <>


07/20/2023 libmodbus v3.1.7 libmodbus Manual