Siemens NAN 67 Series Manual de Serviço descarregar pdf (Página 237)

20-3

Ladder Logic (LAD) for S7-300 and S7-400

C79000-G7076-C504-02

OPN

If the unconditional call of FC10 is executed, the CALL instruction performs the following

functions:

S Saves the address that it needs to return to the current FB

S Saves the selectors for DB10 and for the instance data block of the FB

S Pushes the MA bit, set to 1 in the MCRA instruction, to the block stack (BSTACK) and

resets this bit to 0 for the called FC10

Program processing continues in FC10. If you want to use the MCR function in FC10, you must

reactivate it there. When FC10 is finished, program processing returns to the calling FB. The

MA bit is restored, and DB10 and the instance data block of the user-defined FB are the current

DBs again, regardless of which DBs FC10 used.

After jumping back from FC10 the signal state of input I 0.0 is assigned to output Q 4.0. The call

of FC11 is a conditional call. It is executed only if the signal state of input I 0.1 is 1. If the call is

executed, the function is the same as for calling FC10.

I 0.0

Q 4.0

I 0.1

FC11

DB10

MCRA

CALL

FC10

CALL

Status Word Bits

BR CC 1 CC 0 OV OS OR STA RLO FC

Write – – – – 0 0 1 – 0

MCRD

BR CC 1 CC 0 OV OS OR STA RLO FC

Write – – – – 0 0 1 1 0

Unconditional Call

Conditional Call

Figure 20-1 Call FC/SFC from Coil

Program Control Instructions

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Siemens NAN 67 Series Manual de Serviço Página 237