Technical data

Appendix
27.6 Sample Programs
Programming with STEP 7
646 Manual, 05/2010, A5E02789666-01
27.6.2.4 Creating the FC for the Valves
What is Required of the FC?
The function for the inlet and feed valves and for the drain valve contains the following logical
functions:
• There is an input for opening and an input for closing the valves.
• Interlocks allow the valves to be opened. The state of the interlocks is saved in the temporary
local data (L stack) of OB1 ("Valve_enable") and is logically combined with the inputs for
opening and closing when the FC for the valves is processed.
The following table shows the parameters that must be transferred to the FC.
Parameters for the Valves Input Output In/Out
Open
x
Close
x
Dsp_Open
x
Dsp_Closed
x
Valve
x
Specifying the Inputs and Outputs
The following figure shows the inputs and outputs of the general FC for the valves. The devices
that call the FB for the motor transfer input parameters. The FC for the valves returns output
parameters.