Instructions Created By The Position Control Wizard For The Position Module - Siemens SIMATIC S7-200 System Manual

Instructions Created by the Position Control Wizard for the
Position Module
The Position Control wizard makes controlling the Position module easier by creating unique
instruction subroutines based on the position of the module and configuration options you
selected. Each position instruction is prefixed with a "POSx_" where x is the module location.
Because each position instruction is a subroutine, the 11 position instructions use 11 subroutines.
Tip
The position instructions increase the amount of memory required for your program by up to
1700 bytes. You can delete unused position instructions to reduce the amount of memory
required. To restore a deleted position instruction, simply run the Position Control wizard again.
Guidelines for Using the Position Instructions
You must ensure that only one position instruction is active at a time.
You can execute the POSx_RUN and POSx_GOTO from an interrupt routine. However, it is very
important that you do not attempt to start an instruction in an interrupt routine if the module is busy
processing another command. If you start an instruction in an interrupt routine, then you can use
the outputs of the POSx_CTRL instruction to monitor when the Position module has completed
the movement.
The Position Control wizard automatically configures the values for the speed parameters (Speed
and C_Speed) and the position parameters (Pos or C_Pos) according to the measurement
system that you selected. For pulses, these parameters are DINT values. For engineering units,
the parameters are REAL values for the type of unit that you selected. For example: selecting
centimeters (cm) stores the position parameters as REAL values in centimeters and stores the
speed parameters as REAL values in centimeters per second (cm/sec).
The following position instructions are required for specific position control tasks:
Insert the POSx_CTRL instruction in your program and use the SM0.0 contact to execute it
-
every scan.
To specify motion to an absolute position, you must first use either an POSx_RSEEK or a
-
POSx_LDPOS instruction to establish the zero position.
To move to a specific location, based on inputs from your program, use the POSx_GOTO
-
instruction.
To run the motion profiles you configured with the Position Control wizard, use the
-
POSx_RUN instruction.
The other position instructions are optional.
Open Loop Motion Control with the S7-200 Chapter 9
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