DL250-1 Stage Programming: Configuring a Tank Sequence

The DL250-1 example implements a sequential tank process in two forms: stage programming before the first END instruction and conventional ladder logic afterward. The stage version is the clearer reference because each process state owns its outputs and transfers control when its completion condition becomes true.

Map the documented addresses

The narrative says the process has four tanks, but it defines functions only for tanks 1 through 3. Treat the fourth tank as unspecified until the process documentation identifies it.

Configure the stage sequence

1. Keep S0 active as the initial stage. Transfer to S1 when X100 and the X101 permissive are true.
2. In S1, energize Y0 to fill tank 3 from tank 1. Transfer when the tank level reaches the first setpoint represented by V2000 and V2001.
3. In S2, energize Y1 to fill from tank 2. Transfer when the level reaches the second setpoint represented by V2002 and V2001.
4. In S3, run timer T0 with preset V400 and energize mixer Y3. Transfer to S4 when T0 completes.
5. In S4, energize drain valve Y2. Return to S0 when V2001 equals K0.

A stage output turns off when execution exits that stage. This removes the need for separate state permissives around an output used only in one stage. The evidence identifies the comparisons by their intended process results but does not document mnemonic operand semantics; confirm operand order and comparison direction in the programming software before commissioning.

Resolve the drain-time discrepancy

It keepsY2 on until V2001 equals K0. The only documented timer is T0, whose preset V400 controls mixing.

Choose the required completion rule from the approved process specification: elapsed drain time, confirmed empty level, or another defined condition. Do not describe the current program as a 10-minute drain unless a separate drain timer is added and its time base and preset are verified.

Select and verify the output hardware

The stated load is approximately 25 interposing relays, each rated 24 VDC at approximately 30 mA. The evidence identifies protected transistor modules F2-16TD1P and F2-16TD2P as preferred options, but it does not provide channel ratings, grouping limits, leakage specifications, or wiring details. Verify those values against the selected module documentation and calculate each output-group load before selection.

Field guidance in the evidence estimates relay-output life at about 500,000 cycles under light load and about 100,000 cycles near the load rating; these are not presented as guaranteed DL250-1 specifications. For an oil- or water-exposed machine, protection also depends on enclosure, wiring, and fault containment, so a short-circuit-protected module alone does not establish environmental suitability.

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