Configure D_ACT_DP to Activate PROFINET Devices on S7-1200

Problem Statement: Conditional PROFINET Activation on S7-1200

A flexible S7-1200 program often needs to support more than one runtime topology. A typical requirement is a base configuration that runs on every machine and an extended configuration that adds I/O, drives, or third-party PROFINET devices only when the customer purchases the extra option. The extended hardware (for example a SINAMICS G120 frequency drive) is wired in at the cabinet but is not always powered up or connected.

When a configured PROFINET IO device is unreachable at start-up, the CPU enters a station failure state: the SF (red) LED blinks, the diagnostic interrupt is raised, and any cyclic I/O from that device is set to substitute values (0 for digital, 0 for analog). This is the root of the original problem: the PLC cannot be put into RUN when an optional PROFINET device is missing or powered off.

The legacy S7-300 environment solved this with the D_ACT_DP / DEACT_DPS blocks. The same approach is available on the S7-1200 using the D_ACT_DP instruction in TIA Portal, as confirmed by Siemens Support Entry ID 109741593: "With the D_ACT_DP instruction, you can disable and enable configured PROFINET IO devices in a targeted manner."

How PROFINET Reacts to a Missing Device

PROFINET IO communication is supervised by the IO controller (the S7-1200 CPU) using AR (Application Relationship) and CR (Communication Relationship) state machines defined in IEC 61784-2. Once the controller has accepted a device into the configured slot, it expects an AR to come up within the configured Device Replacement Timeout (TIA Portal default usually 600 ms, configurable up to several seconds). If the AR does not appear or disappears, the device transitions to a station-fault state and the CPU raises diagnostic interrupts.

This is why simply leaving a device configured but disconnected causes a red BF/MF LED pattern and propagates a station fault into the diagnostic buffer. D_ACT_DP deliberately withdraws the configured slot from active I/O exchange, putting the relationship into a "deactivated" state where the controller no longer expects the AR to come up.

Solution Overview: D_ACT_DP

D_ACT_DP is a standardized block used uniformly across S7-300, S7-400, S7-1200, and S7-1500. The CPU keeps the device configuration in its project but deactivates the cyclic data exchange at runtime.

• Configured devices stay in the HW configuration and the diagnostic tree.
• Calling D_ACT_DP with MODE = 2 deactivates the device; no station fault is raised for it.
• Calling D_ACT_DP with MODE = 1 re-activates the device; the AR is re-established and IO exchange resumes.
• MODE = 0 queries the current activation status without changing it.

This mechanism is not the same as removing the device from the project; the device is "known" but "not in service". For S7-1200, the instruction is in the standard TIA Portal library and is supported on CPUs with firmware V4.x. Use TIA Portal V16 SP1 or newer for full alignment with current documentation.

Prerequisites and Configuration Environment

1. CPU: SIMATIC S7-1200, firmware V4.2 or higher (V4.4 recommended for full feature parity with PROFINET V2.4). C-, F-, and T-CPU variants are supported.
2. Engineering: TIA Portal V16 SP1 or newer (V17 / V18 acceptable). The D_ACT_DP block lives under Instructions > Communication > PROFINET / PROFIBUS.
3. Optional PROFINET devices must be configured in the device configuration of the S7-1200 (drag in GSD or HSP). D_ACT_DP cannot activate a device that has not been configured.
4. The CPU must be in RUN for activation/deactivation; D_ACT_DP is executable from OB1, OB82 (diagnostic interrupt), OB100 (restart), or a watchdog OB.
5. For an external HMI (for example a Beijer KPT-600 PN via PROFINET), the protection page mechanism is independent of D_ACT_DP; only a flag triggers which mode the PLC runs in.

D_ACT_DP Interface Definition

LADDR (HW Identifier) Capture

The HW identifier is a numeric or symbolic handle assigned by TIA Portal. In the Devices & networks editor, right-click the PROFINET device > Properties > System constants, and tick Show. The constant appears under Name of the PROFINET IO device, e.g. "G120_CU240E_2_PN~PN-IO-Device~Head". Some projects use an IO slot handle such as 268; both forms are valid inputs.

Step-by-Step Implementation in TIA Portal

1. Open the project and ensure the optional PROFINET device is configured and connected to the S7-1200 PROFINET interface (X1 or X2) in Devices & networks.
2. Add an instance DB by dragging D_ACT_DP from Instructions > Communication > S7 Communication or PROFINET into a function block (recommended: an FB so the tags are reusable per call). Assign an instance DB, e.g. iDB_DACT_G120.
3. Create a global data block ConfigMode with:
   • bExtendedActive : BOOL — set from the HMI protected page (protected via the Beijer KPT-600 user rights).
   • bStartOneShot : BOOL — single-cycle pulse from the HMI button or from the startup logic.
   • wDACT_Status_G120 : WORD — feedback from STATUS.
   • iDACT_RetVal_G120 : INT — feedback from RET_VAL.
4. Wire the call. In OB1 (or a dedicated FB), use SCL or ladder:

// Reset detect on ExtendedActive, rising-edge on bStartOneShot
IF "ConfigMode".bExtendedActive THEN
    // Activate the optional drive if not yet active
    "iDB_DACT_G120".D_ACT_DB(REQ := "ConfigMode".bStartOneShot,
                             MODE := 1,        // 1 = activate
                             LADDR := "G120_CU240E_2_PN~PN-IO-Device~Head",
                             RET_VAL => "ConfigMode".iDACT_RetVal_G120,
                             BUSY   => bBusyAct,
                             STATUS => "ConfigMode".wDACT_Status_G120);
ELSE
    // Extended option off, deactivate drive to avoid station fault
    "iDB_DACT_G120".D_ACT_DB(REQ := "ConfigMode".bStartOneShot,
                             MODE := 2,        // 2 = deactivate
                             LADDR := "G120_CU240E_2_PN~PN-IO-Device~Head",
                             RET_VAL => "ConfigMode".iDACT_RetVal_G120,
                             BUSY   => bBusyDeact,
                             STATUS => "ConfigMode".wDACT_Status_G120);
END_IF;

5. Handle BUSY properly: REQ must remain TRUE while BUSY is TRUE; otherwise the call aborts.
6. Establish the start conditions:
   • Set bExtendedActive from the HMI after successful login to the protected page.
   • Generate a 1-cycle pulse in bStartOneShot on a rising edge of bExtendedActive. Use the startup logic in OB100 to deactivate the device before the first PROFINET AR scan completes.
7. Compile and download the project (hardware and software). Re-start the CPU when prompted.

First-Run Behavior Without the Drive

When the G120 is not connected (or not energized) and bExtendedActive = FALSE, call D_ACT_DP with MODE := 2 in OB100. The PROFINET AR is not opened, so the CPU does not raise a station fault and the SF LED stays off. This is the sequence that makes the S7-1200 behave like an S7-300 with a deactivated slave.

SINAMICS G120 Integration Specifics

The drive is identified by a GSD file in TIA Portal (or via HSP). Common PROFINET-capable control units include:

Star or line topology is acceptable on the PROFINET switch. When the G120 is wired but not energized, keep its ports empty of cables downstream (no downstream IO). If the drive is in a deeper ring line, connect it via a PROFINET switch, not inline with the IO line, so the AR failure of the drive does not propagate station faults to other devices.

The G120 takes roughly 3-5 seconds to come ready on PROFINET from power-up. Configure the Watchdog time in the device properties > PROFINET interface > Port statistics to at least 1000 ms to ride out the start window. D_ACT_DP MODE = 2 should be issued before the watchdog expires.

HMI Integration with a Beijer KPT-600

The KPT-600 is a Beijer Electronics HMI (iX series or similar PN-enabled terminal). It connects to the S7-1200 over PROFINET or Modbus TCP (suitable PROFINET/Modbus tags). The "protected page" concept maps to:

• User-rights login on the HMI.
• Set tag bExtendedActive = TRUE on the PLC after successful login.
• Set tag back to FALSE on logout, timeout, or "switch to base mode" button.

The HMI should also display the status returned by D_ACT_DP:

// Compact status word: high byte = BUSY, low byte = activate/deactivate mode
wActReady = (ConfigMode.wDACT_Status_G120 = 16#0000) AND NOT bBusy;

D_ACT_DP Return / Status Codes

Verification Procedure

1. With bExtendedActive = FALSE and the G120 unpowered, download the project to the S7-1200, perform a restart, and confirm the SF LED is OFF. The diagnostic buffer should not contain a station-fault entry for the G120.
2. Set bExtendedActive = TRUE from the HMI. Verify the SF and BF LEDs remain off, the G120 reports cyclic exchange OK (monitor 0x6999 status word or the IO status in TIA Portal online), and RET_VAL = 0 within ~1 s.
3. Drop the line to the G120 while the drive is activated. Observe a station fault within the watchdog time (default 600-1000 ms). The CPU must not switch to STOP; configure the OB82 diagnostic OB to keep RUN mode active.
4. Re-set bExtendedActive = FALSE and call D_ACT_DP with MODE = 2. The station fault must clear in the diagnostic buffer within one refresh cycle and the SF LED must go off.
5. Cycle power to the CPU and verify the start mode matches the last saved bExtendedActive in the instance DB. For a cold restart, integrate the activation/deactivation in OB100 with a retained flag.

Comparison: S7-300 vs. S7-1200 vs. S7-1500

Troubleshooting Matrix

Field-Commissioning Checklist

1. Confirm the G120 GSDML file version matches the firmware (use a current GSDML without losing diagnostics; pin to a tested version if multi-protocol coexistence is needed).
2. Assign a unique PROFINET device name to every G120 in the cabinet (default name from GSD is fine for one machine, but multiple machines must differ).
3. Tune the watchdog time on each PN device to 1000 ms or more before the system integrator signs off.
4. Verify the KPT-600 HMI does not issue bExtendedActive until user-rights authentication is complete.
5. Add a watchdog in OB1: if bExtendedActive = TRUE and the drive is missing for more than 30 s, automatically roll back to FALSE.
6. Save a remote backup of the TIA project for firmware updates; D_ACT_DP behavior is binary-compatible across V16-V18.
7. Document the activation behavior in the operator manual; inexperienced operators may not understand why a screen sometimes shows fewer controls.

Safety and PROFIsafe Considerations

If the G120 is in a F-CPU environment and uses PROFIsafe, do not deactivate it via D_ACT_DP while the safety program requires the drive. A deactivated PROFIsafe slot transitions the F-system to PASSIVATED and triggers a safety stop. Move drive activation out of the SIL path and keep the safety I/O on a separate F-CPU or on fixed-IO hardware.

Alternatives to D_ACT_DP on S7-1200

• Two projects: keep a "base" and an "extended" TIA project. Acceptable for variants, costly for software updates.
• Option handling: use macros or software option keys on the HMI to gate logic but keep all PROFINET devices configured and active. Requires the device to be physically present and powered.
• Standalone IO: relocate drive control to ET 200SP PN that is physically present; reserve D_ACT_DP only for optional sensors and handhelds.
• Conditional configuration: TIA Portal V16 introduced variant-based hardware configuration that gates module-level behavior, but it is a compile-time mechanism, not a runtime deactivation.

FAQ