Siemens NAN 67 Series Manual de servicio descargar pdf (Pagina 233)

19-9

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

C79000-G7076-C504-02

19.6 Exception Bit Overflow Stored

You can use the Exception Bit Overflow Stored instruction to recognize a

latching overflow (overflow stored, OS) in a math function. If, after the

system executes a math function, the result is outside the permissible

negative range or outside the permissible positive range, the OS bit in the

status word (see Section 6.3) is set. The instruction checks the signal state of

this bit. Unlike the OV (overflow) bit, the OS bit remains set by error-free

running math functions (see Section 19.5).

When used in series, this instruction combines the result of its check with the

previous result of logic operation (RLO) according to the And truth table

(see Section 6.2 and Table 6-8). When used in parallel, this instruction

combines the result of its check with the previous RLO according to the Or

truth table (see Section 6.2 and Table 6-9).

Figure 19-9 Exception Bit Overflow Stored Element and Its Negated Form

Description

The Element and

Its Negated Form

Status Bit Instructions

1 2 ... 228 229 230 231 232 233 234 235 236 237 238 ... 317 318

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Siemens NAN 67 Series Manual de servicio Pagina 233