Siemens SIMATIC S7-200 System Manual page 288

S7-200 Programmable Controller System Manual
POSx_CTRL Instruction
The POSx_CTRL instruction (Control) enables and
initializes the Position module by automatically commanding
the Position module to load the configuration/profile table
each time the S7-200 changes to RUN mode.
Use this instruction only once in your project, and ensure
that your program calls this instruction every scan. Use
SM0.0 (Always On) as the input for the EN parameter.
The MOD_EN parameter must be on to enable the other
position instructions to send commands to the Position
module. If the MOD_EN parameter turns off, then the
Position module aborts any command that is in progress.
The output parameters of the POSx_CTRL instruction
provide the current status of the Position module.
The Done parameter turns on when the Position module
completes any instruction.
The Error parameter contains the result of this instruction.
See Table 9-20 for definitions of the error codes.
The C_Pos parameter is the current position of the module. Based of the units of measurement,
the value is either a number of pulses (DINT) or the number of engineering units (REAL).
The C_Speed parameter provides the current speed of the module. If you configured the
measurement system for the Position module for pulses, C_Speed is a DINT value containing the
number of pulses/second. If you configured the measurement system for engineering units,
C_Speed is a REAL value containing the selected engineering units/second (REAL).
The C_Dir parameter indicates the current direction of the motor.
Table 9-9 Parameters for the POSx_CTRL Instruction
Inputs/Outputs
MOD_EN
Done, C_Dir
Error
C_Pos, C_Speed
Tip
The Position module reads the configuration/profile table only at power-up or when commanded
to load the configuration.
H If you use the Position Control wizard to modify the configuration, then the POSx_CTRL
instruction automatically commands the Position module to load the configuration/profile
table every time the S7-200 CPU changes to RUN mode.
H If you use the EM 253 Control Panel to modify the configuration, clicking the Update
Configuration button commands the Position module to load the new configuration/profile
table.
H If you use another method to modify the configuration, then you must also issue a Reload
the Configuration command to the Position module to load the configuration/profile table.
Otherwise, the Position module continues to use the old configuration/profile table.
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Data Type Operands
BOOL I, Q, V, M, SM, S, T, C, L, Power Flow
BOOL I, Q, V, M, SM, S, T, C, L
BYTE IB, QB, VB, MB, SMB, SB, LB, AC, *VD, *AC, *LD
DINT, REAL ID, QD, VD, MD, SMD, SD, LD, AC, *VD, *AC, *LD