SINUMERIK 840C: Converting 840D Conditional Branching

A SINUMERIK 840D program calculates the difference between R24 and R25, branches forward when the result is positive, and otherwise displays an operator message, pauses, and branches backward. Porting this sequence to an 840C requires translating both the branch syntax and the message/pause behavior; the available evidence does not provide a complete, verified one-to-one conversion.

840D Logic to Preserve

N5 ABBRUCH:
N10 R1=R24-R25
N15 IF (R1>0) GOTOF FRAESEN
MSG ("R25 TOO LARGE")
N20 M0
N25 GOTOB ABBRUCH
N30 FRAESEN

The intended decision is explicit: calculate R1 = R24 - R25. If R1 > 0, continue at FRAESEN. Otherwise, issue the message, execute M0, and return to ABBRUCH. Preserve that behavior even if the 840C implementation uses different commands or label conventions.

840C Elements Requiring Manual Verification

The evidence identifies @126, R50, R51, and K9002 as relevant 840C manual entries, but it does not define their syntax or prove a direct mapping. Confirm each entry in the manual for the installed 840C configuration before editing the production program.

Conversion and Verification Procedure

1. Document the original state flow: subtract, test for a positive result, branch to machining, or display a message and stop before returning to the test.
2. Use the 840C manual entries for @126, R50, R51, and K9002 to build the equivalent conditional and operator-notification sequence. Do not assume that 840D labels, GOTOF, GOTOB, or MSG are accepted unchanged.
3. Test both decision outcomes without machining: one case where R24-R25>0 and one where that condition is false.
4. Verify the positive case reaches the machining path. Verify the other case presents the intended notification, executes the stop, and returns to the comparison path only after the permitted restart action.

Acceptance Criteria

Accept the conversion only when the calculation uses the intended R parameters, both branches reach the correct destinations, the non-positive path cannot enter machining, and the operator message and stop occur in the required order. The evidence is insufficient to publish executable 840C replacement code; doing so without the applicable manual definitions would introduce unsupported syntax and behavior.

FAQ