S5 AWL Commands: +F, -F, +G (Integer Arithmetic)

S5 AWL arithmetic operates on the two accumulators: ACCU2 (operator) and ACCU1 (operand). The result goes into ACCU1. ACCU2 is unchanged.

Instructions#

Code Example — Add Two Values#

L  MW 10            // Load first value → ACCU1
L  MW 20            // First value moves to ACCU2, second → ACCU1
+F                  // ACCU1 = MW10 + MW20 (INT addition)
T  MW 30            // Store result

S7 STL: L MW 10 / L MW 20 / +I / T MW 30 (identical logic, different mnemonic)

S7 SCL: MW30 := MW10 + MW20;

Important: Operand Order#

The first L goes into ACCU2 (after the second L pushes it there). The second L is in ACCU1. For subtraction: ACCU2 - ACCU1 = first loaded - second loaded.

L  MW 10            // 100 → ACCU1, then pushed to ACCU2
L  MW 20            // 30 → ACCU1
-F                  // ACCU1 = 100 - 30 = 70
T  MW 30            // MW30 = 70

Overflow Detection#

After +F/-F, the overflow flags (OV, OS) indicate if the result exceeded the INT range. Check with:

+F
SPO =OVERFLOW       // Jump if overflow occurred

S7 Equivalents Summary#

Part of the S5 AWL Command Reference. Maintained by PLCcheck.ai.

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