I2C_PCF8574_read block

Short summary

Name	`I2C_PCF8574_read`
→POU type	→function
Category	more system blocks, blocks for I2C elements
Graphical interface
Available since	version 1.13.0 (for Neuron Power Engineer) and version 2.3.901 of Neuron RTS max This block is supported for →Raspberry Pi only. version 1.109.0 (for Neuron Power Engineer) and version 3.19.0 of Neuron RTS max This block is supported for Raspberry Pi and the platform `LinuxX86` only.

The block reads the states of inputs from PCF8574 (→I2C port expanders).

For more information on the PCF8574 chip see for example: http://www.nxp.com/documents/data_sheet/PCF8574.pdf (product specification by manufacturer NXP)

	Identifier	→Data type	Description
Inputs:	`fd`	`DINT`	the handle for the I2C device file opened by the `I2C_Open block`
Inputs:	`address`	`INT`	the I2C address of the PCF8574 (port expander)
Return value:	–	`ARRAY[0..7] OF BOOL`	returns the states of the pins of the PCF8574 (port expander)

Input EN and output ENO are available when →calling the block. See "Execution control: EN, ENO" for information on input EN and output ENO.

See:

"Blocks for safe logic" whether this block is supported for developing safety-relevant applications.
"Highlighting safe logic in the FBD-editor" for the effects when using the block as a block for safe logic.

PROGRAM Test

VAR

    handle : DINT := -1;

    digitals : ARRAY[0..7] OF BOOL;

END_VAR;

ENO := TRUE;

IF handle < 0 THEN

    handle := I2C_open(bus_id := 1, ENO => ENO);

ELSIF ENO THEN

        digitals := I2C_PCF8574_read(fd := handle, address := 56, ENO => ENO);

END_IF;

END_PROGRAM

When creating your application within the ST-editor, enter a call of a block by typing the text as requested by the syntax or use Content Assist.