owSearchX (Function)

Top Previous Next

Architecture:	X32 / NX32 / NX32L
Device support:	All devices with 1-Wire
Firmware version:	2.80 / 1.00.00

An advanced version of the owSearch function that allows detection of all 1-Wire devices on the bus which belong to the specified families.

Each 1-Wire device has a unique ROM-number like the iButton. This number is used to point out one specific device of many devices on the bus.

Before any devices can be accessed, the ROM-number has to be discovered. By using the 1-Wire search function, all devices on the 1-Wire bus are discovered and the ROM-numbers are stored in a temporary list placed inside the RTCU device.

The list of known devices will be update when the following functions are called:

owSearchX

owSearch

owiButtonGetID

The devices are sorted in the order they are discovered on the 1-Wire net. If a device is removed from the bus, all devices after this will move one position down the list when a new search is carried out As the search function is intended for general 1-Wire use, a family number can be supplied when making the function call to optimize the search.

Current official list of Maxim 1-Wire family codes:

	16#01	DS1990A, DS1990R, DS2401, DS2411.
	16#02	DS1991.
	16#04	DS1994, DS2404.
	16#05	DS2405.
	16#06	DS1993.
	16#08	DS1992.
	16#09	DS1982, DS2502.
	16#0A	DS1995.
	16#0B	DS1985, DS2505.
	16#0C	DS1996.
	16#0F	DS1986, DS2506.
	16#10	DS1920.
	16#12	DS2406, DS2407.
	16#14	DS1971, DS2430A.
	16#1A	DS1963L.
	16#1C	DS28E04-100.
	16#1D	DS2423.
	16#1F	DS2409.
	16#20	DS2450.
	16#21	DS1921G, DS1921H, DS1921Z.
	16#23	DS1973, DS2433.
	16#24	DS1904, DS2415.
	16#27	DS2417.
	16#28	DS18B20.
	16#29	DS2408.
	16#2C	DS2890.
	16#2D	DS1972.
	16#37	DS1977.
	16#3A	DS2413.
	16#41	DS1922L, DS1922T, DS1923, DS2422.
	16#42	DS28EA00.
	16#43	DS28EC20.

To optimize the search time, only conduct a single search for all devices.

Input:

first : INT [0..255] (default 0)

Skips devices with lower family codes.

last : INT [0..255] (default 255)

Does not search for devices with higher family codes than this.

reset : BOOL [TRUE, FALSE] (default TRUE)

Deletes all known devices before search.

Returns: INT

>= 0		Number of devices found within family range.
-1		General error or not supported on target.

Declaration:

FUNCTION owSearchX : INT;
VAR_INPUT
first : INT := 16#00;
last : INT := 16#FF;
reset : BOOL := TRUE;
END_VAR;

Example:

Please see the "Examples - Generic OneWire Example"