S5 AWL Command: SPB (Conditional Jump if TRUE)

SPB jumps to a label only if the VKE is TRUE. If VKE is FALSE, execution continues with the next instruction. SPB is the primary conditional branching mechanism in AWL — it implements IF/THEN logic.

Syntax#

U   E 0.0          // Condition
SPB =M001          // Jump to M001 if E 0.0 is TRUE

S7 Equivalent#

Code Example — IF/THEN#

U   E 0.0          // IF E 0.0
SPB =M001          // THEN jump to M001
SPA =M002          // ELSE jump to M002 (skip THEN block)

M001: L KF +100    // THEN: load 100
T   MW 20
SPA =M099          // Jump to end

M002: L KF +0      // ELSE: load 0
T   MW 20

M099: NOP 0        // Continue

SCL equivalent: IF E0_0 THEN MW20 := 100; ELSE MW20 := 0; END_IF;

VKE After SPB#

• If jump is taken (VKE was TRUE): VKE is set to 1 at the target label
• If jump is not taken (VKE was FALSE): VKE remains 0, execution continues

Common Patterns#

Related: SPA (Unconditional) | SPBN (Jump if NOT)#

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

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