Siemens SIMATIC S7-200 System Manual page 277

PTOx_LDPOS Instruction
The PTOx_LDPOS instruction (Load Position) changes the
current position value of the PTO pulse counter to a new
value. You can also use this instruction to establish a new
zero position for any move command.
Turning on the EN bit enables the instruction. Ensure that
the EN bit stays on until the Done bit signals that the
execution of the instruction has completed.
Turning on the START parameter loads a new position into
the PTO pulse counter. For each scan when the START
parameter is on and the PTO is not currently busy, the
instruction loads a new position into the PTO pulse counter.
To ensure that only one command is sent, use an edge
detection element to pulse the START parameter on.
The New_Pos parameter provides the new value to replace
the current position value that is reported. The position
value is expressed as a number of pulses.
The Done parameter turns on when the module completes this instruction.
The Error parameter contains the result of this instruction. See Table 9-7 for definitions of the error
codes.
The C_Pos parameter contains the current position of the module as the number of pulses if the
HSC was enabled in the wizard. Otherwise the current position is always 0.
Table 9-6 Parameters for the PTOx_LDPOS Instruction
Inputs/Outputs
START
New_Pos, C_Pos
Done
Error
Open Loop Motion Control with the S7-200
Data Types Operands
BOOL I, Q, V, M, SM, S, T, C, L, Power Flow
DINT ID, QD, VD, MD, SMD, SD, LD, AC, *VD, *AC, *LD
BOOL I, Q, V, M, SM, S, T, C, L
BYTE IB, QB, VB, MB, SMB, SB, LB, AC, *VD, *AC, *LD
Chapter 9
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