WinCC DowntimeMonitor: S7-315-2DP PROFIBUS and ERP Connectivity

1. System Architecture Overview

The reference architecture for a beverage production line that aggregates downtime, efficiency, speed, and KPI data from eighteen SIMATIC S7-315-2DP controllers into an enterprise-facing reporting layer has four distinct tiers:

1. Control tier: Eighteen S7-315-2DP CPUs running the line PLC programs. Each CPU exposes the PROFIBUS DP master interface on the front X2 port and a second MPI/DP combined port on X1.
2. Fieldbus tier: A PROFIBUS DP backbone terminated with 9-pin D-sub connectors, 120 Ω terminating resistors switched ON at both physical ends, and one or more RS-485 repeaters (e.g. 6GK1500-0AA10) if the line length or station count exceeds the segment budget.
3. Supervisory tier: A single WinCC station (or WinCC Redundant server pair) that runs WinCC DowntimeMonitor as a WinCC option, communicating to the PROFIBUS network through a CP 5611 (6GK1561-1AA01) or the modern PCI-Express successor CP 5621 (6GK1562-1AA00).
4. IT/ERP tier: An OPC HDA / OPC AE consumer running WinCC Connectivity Pack, or a custom SQL consumer reading WinCC archive tables through the Industrial Data Bridge option.

The DowntimeMonitor option itself is an add-on that ships with the WinCC DVD media (folder \WinCC\Options\DowntimeMonitor) and is enabled with a separate license key, normally a Counted Objects license referenced by the WinCC License Manager under the tag ASIA-DT-MON on legacy media, or a SIEMENS WinCC DowntimeMonitor license block in TIA Portal / Automation License Manager for current versions.

2. Hardware Selection: CP 5611, CP 5621, or Softnet

Install the SIMATIC NET PC software (2020 SP2 or newer, edition 2008 for legacy stacks) before inserting the CP. The Configuration Console must list the CP with a station address that is unique on the bus (typical default: 0 for the master). Set the bus profile to DP master class 1; the WinCC driver PROFIBUS DP (channel DLL: PDPMCSP.DLL) registers a S7-Connection per DP slave.

3. PROFIBUS DP Network Sizing for 18 PLCs

PROFIBUS DP supports 32 stations per electrical segment, and 126 stations across four segments with repeaters. The bus parameters for 1.5 Mbit/s (the most common industrial rate for SCADA polling) are:

At 1.5 Mbit/s the bit time t_BIT is 0.667 µs, so T_TR = 3 000 × 0.667 µs ≈ 2 ms. With 18 slaves and average 4 bytes of cyclic I/O per slave, the expected scan cycle is on the order of 5-15 ms; this is the upper bound for any high-speed KPI such as instantaneous OEE availability. If the application requires 100 ms KPI updates, the existing 1.5 Mbit/s design is comfortable. If you need sub-50 ms KPI updates for all 18 PLCs simultaneously, switch to PROFINET and re-evaluate the design - 18 PROFINET IO devices on a single S7-315-2PN/DP CPU is not feasible; the 315-2DP does not have a PROFINET port.

4. WinCC DowntimeMonitor: What It Is, and What It Is Not

WinCC DowntimeMonitor is a WinCC option, not a standalone product. It installs as a child of the WinCC Runtime database and provides:

• A pre-configured WinCC picture set (Overview, Line Down, Cause Frequency, Status Distribution, Top 5 Reasons) bound to the project function DTMMain.
• A standard interface for connecting machine-level down signals. Each machine is exposed as a structure with the tags State, Speed, Rate, ChangeTime, and the reason tags Reason1..Reason32.
• SQL Server archive tables DTMD_MachineState, DTMD_ReasonAssignment, DTMD_ShiftLog, and DTMD_KPI that are written by the WinCC runtime via cyclic logging.
• Predefined calculations for OEE Availability, OEE Performance, and OEE Quality, exposed as structure tags of type DTMC_KPI.

DowntimeMonitor requires only the WinCC Runtime license plus the DowntimeMonitor option license; it does not require WinCC Industrial Data Bridge, WinCC Connectivity Pack, or any other add-on for the data acquisition path into the WinCC archive. The release notes confirm that the DowntimeMonitor server cannot be configured as a redundant server pair: when installed on a WinCC redundant server configuration, the option must be installed and licensed on one of the two WinCC servers, and the partner server is not a hot standby for the option itself. See the official WinCC DowntimeMonitor release notes.

5. PLC-Side Preparation on the S7-315-2DP

Each S7-315-2DP CPU publishes its data on the integrated DP master port (X2). To make the data available to WinCC, the engineer must choose one of two patterns:

1. Direct S7-Connection per CPU. The WinCC channel SIMATIC S7 Protocol Suite opens a S7-Connection to each CPU. The CP 5611 acts as a DP master, the S7-315-2DP as a DP slave on the same bus. The PG/PC interface in the Configuration Console is set to CP5611(DP-Master), and the bus is configured in HW Config with the S7-315-2DP station set to DP-Slave and a slot for Universal module that defines the exchange area (typically 16 bytes of inputs, 16 bytes of outputs is sufficient for the DowntimeMonitor state structure).
2. DP master to a single PG/PC, S7 routing in the PLC. This is the only feasible pattern when the S7-315-2DP station also acts as a DP master to local ET200 slaves. The PLC exposes a S7-Connection endpoint over the X2 DP port and WinCC polls each PLC's data block directly using S7 put/get (function group BSEND/BRCV is not required for WinCC; raw DB read suffices).

The data block layout that the DowntimeMonitor state structure expects on the PLC side is shown below. The PLC programmer should match this layout exactly to avoid datatype conversion errors in WinCC:

DATA_BLOCK "DB_DTM_State"
  STRUCT
    State         : INT;   // 0=Run, 1=Down, 2=Setup, 3=Changeover
    Speed         : REAL;  // Actual machine speed [units/min]
    Rate          : REAL;  // Theoretical max rate [units/min]
    ChangeTime    : DTL;   // Last state change timestamp
    GoodCount     : DINT;  // Quality pass counter
    BadCount      : DINT;  // Quality reject counter
    Reason1       : BOOL;  // Reason bit 1 active
    Reason2       : BOOL;  // Reason bit 2 active
    ... up to Reason32
  END_STRUCT
END_DATA_BLOCK

For each of the 18 PLCs create a matching S7 connection named S7_DTM_PLC01 through S7_DTM_PLC18 in the WinCC Logical Device Names. Use a CP 5611.1 address per connection (the bus address of the S7-315-2DP on the DP segment) and a Rack/Slot of 0/2 for the integrated DP port.

6. WinCC DowntimeMonitor Installation and Project Wiring

1. Insert the WinCC V7.x DVD and run Setup. Under WinCC Options select DowntimeMonitor. If the installation is on a WinCC server, select the Server component. The installer copies the option into %ProgramFiles(x86)%\Siemens\Automation\WinCC\Options\DowntimeMonitor.
2. Open the WinCC Explorer and load the project DTMDemoProject.MCP from the option installation directory. Save it as your project under a new name (e.g. BeverageLine_18PLC.MCP).
3. Open the Tag Management and locate the structure tags DTM_Machine01..DTM_Machine18. For each, set the connection to the corresponding S7-Connection (S7_DTM_PLC01..S7_DTM_PLC18) and map the State, Speed, Rate, GoodCount, BadCount, and Reason1..Reason32 tags to the matching offsets in the PLC DB. Use S7-300/400 address type DB with the configured DB number.
4. Open the picture DTM_Overview.pdl. It already contains 18 placeholder rectangles; right-click each and select Configuration > Machine, then assign one of the structure tags.
5. Open Computer > Properties > Startup and add the DowntimeMonitor runtime module DTMRuntime.exe to the WinCC startup list with delay 30 s after the WinCC Runtime starts. This sequencing prevents the runtime from attempting to log to the SQL Server archive before WinCC has finished opening it.
6. Activate the project. The first archive run writes a baseline row to DTMD_MachineState. Verify by running SELECT TOP 10 * FROM DTMD_MachineState ORDER BY ChangeTime DESC against the WinCC archive database.

7. WinCC Connectivity Pack: OPC HDA, OPC AE, OPC DA

Connectivity Pack is the WinCC option that opens the historical archive to OPC consumers. It installs three separate OPC servers on the WinCC machine:

HDA stands for Historical Data Access and provides the ReadRaw, ReadProcessed, ReadAtTime, and ReadAttribute methods. AE stands for Alarm & Events and provides subscription-based streaming of alarm acknowledgements. Both protocols are exposed by the Connectivity Pack under the Windows DCOM rules; modern deployments should enable OPC UA bridging via the SIMATIC OPC UA Companion Specification gateway where the ERP supports it, because DCOM is firewall-unfriendly.

8. WinCC Industrial Data Bridge: SQL Alternative

WinCC Industrial Data Bridge is a thin middleware that runs as a Windows service and exposes the WinCC archive SQL tables to external consumers. It is essentially a configurable patch panel between an internal source (the WinCC archive SQL Server) and an external destination (an ERP SQL Server, an MQTT broker, a flat file, a REST endpoint). The tool reads the source schema from a defined view in the WinCC archive database and writes to the destination either as bulk insert, transaction-by-transaction, or as polling-based delta.

Use Industrial Data Bridge when:

• The ERP cannot speak OPC HDA. SAP, Oracle SCM, and most MES suites do not implement HDA natively and prefer direct table access.
• The integration team wants to ship flat files (CSV) for an off-line ERP loader.
• The WinCC archive is the only acceptable source of truth and the ERP cannot tolerate a parallel historian.

Industrial Data Bridge cannot replace Connectivity Pack for streaming use cases, and it cannot trigger an event back into WinCC - it is a unidirectional data pump. It is licensed as a WinCC option (license tag ASIA-IDB legacy, or a SIEMENS WinCC Industrial Data Bridge ALM block for current versions). The product has been discontinued in WinCC V8 / TIA WinCC and replaced by the SIMATIC WinCC / IndustrialDataBridge successor built on the same engine, but the install footprint and configuration UI are identical.

9. Decision Matrix: Connectivity Pack vs. Industrial Data Bridge

For a typical SAP or Microsoft Dynamics ERP, Industrial Data Bridge is the lower-risk path. For a modern microservice ERP that already speaks OPC UA over a single TCP port 4840, Connectivity Pack with the SIMATIC OPC UA gateway is lower effort.

10. Step-by-Step: Publishing DowntimeMonitor Data to OPC HDA

1. Open the WinCC project and add the Connectivity Pack option. Install license in ALM and restart the WinCC Runtime.
2. Open the Tag Logging editor. For each of the 18 machine structures, add archive tags for the runtime values State, Speed, Rate, GoodCount, BadCount. Use a 1 s acquisition cycle and a 1 day archiving cycle. Reason bits can be archived on change only (event-based), with a maximum of 100 ms scan rate.
3. Confirm that the archive tables MCPDat, MCPTag, MCPAlarm are present in the WinCC SQL archive. Connectivity Pack will read these tables when the OPC HDA server is queried.
4. On the WinCC server, open dcomcnfg and add the OPC.SimaticHDA.Server.1 application. Grant ANONYMOUS LOGON if the OPC client cannot authenticate; otherwise add the ERP service account to the launch and access permissions. The release notes recommend running both the WinCC station and the OPC consumer on the same Windows domain, ideally behind a single firewall.
5. From the ERP OPC client, navigate to Server > Connect and select OPC.SimaticHDA.Server.1 on the WinCC host. Browse for the DTM_MachineXX.Speed tags.
6. Test with an OPC HDA test client (e.g. OPC HDA Explorer from the OPC Foundation .NET Sample bundle). Issue a ReadRaw for the last 24 hours and verify values match the SQL archive.

11. Step-by-Step: Pumping DowntimeMonitor SQL to an ERP SQL Server

1. Install Industrial Data Bridge on a separate Windows host (or co-locate on the WinCC server - the option supports both; co-location is simpler for small deployments).
2. Create a Source definition in the Industrial Data Bridge Configuration UI. The connection string is the WinCC archive SQL Server: Provider=SQLNCLI11;Data Source=WINCCSRV;Initial Catalog=CC_BeverageLine_18PLC_2024_04_03_11_22_15;Integrated Security=SSPI. The catalog name uses the WinCC pattern CC_<ProjectName>_<CompileStamp>.
3. Define the table mapping. The recommended view is a stored procedure usp_DTMD_Export that flattens DTMD_MachineState and DTMD_ReasonAssignment into a single wide row per minute. The primary key in the destination is (MachineID, ChangeTime) for an idempotent upsert.
4. Create a Destination definition for the ERP SQL Server, with the connection string of the ERP service account and a write schema that matches the destination ERP table.
5. Wire the two with a Job that runs every 60 s and a Trigger that fires on a row count change in the WinCC archive. The job is a one-way data pump; the ERP must not write back to the same row.
6. Validate by running the job once with Dry-Run and inspecting the log file %ProgramData%\Siemens\Automation\IDB\Logs\<JobName>.log.

12. Performance and Sizing Estimates

For 18 machines with a 1 s acquisition cycle, 6 archive tags per machine, plus event-based reason bits:

PROFIBUS bus load is comfortably below the 40 % recommended ceiling; OPC HDA latency is acceptable for shift-level reporting; Industrial Data Bridge latency is acceptable for hourly and daily KPI rollups. If the ERP needs a sub-10 s latency, switch the integration to OPC AE / DA streams from Connectivity Pack and skip the SQL archive step entirely.

13. Redundancy and High Availability

Per the official release notes, the WinCC DowntimeMonitor server cannot be configured as a redundant server pair. In a WinCC redundant server configuration (WinCC/Redundant), the DowntimeMonitor option must therefore be installed and licensed on only one of the two servers. If that server fails, the partner server continues to run the WinCC Runtime and the basic WinCC redundancy maintains user archive values, but the DowntimeMonitor archive and KPI rollups are unavailable until the primary is restored.

For high-availability in the IT/ERP tier, the recommended mitigation is to mirror the WinCC archive SQL Server to a secondary instance with SQL Server Always On, then let the Industrial Data Bridge job read from the secondary. The OPC HDA path has no built-in redundancy, but the OPC client can be configured to fail over to a secondary WinCC Connectivity Pack server if the primary DCOM endpoint is unreachable.

14. Security and Network Segmentation

PROFIBUS DP is an unauthenticated, unencrypted bus. Treat the SCADA VLAN as trust-zero: no direct routing from the office network, no inbound access from the ERP segment. Allow only outbound OPC HDA connections from the SCADA segment to the ERP server, on TCP port 135 (DCOM) plus the dynamic RPC range (49152 - 65535 by default) or, when OPC UA bridging is available, on TCP port 4840. The Windows account running the OPC HDA server should have read-only access to the WinCC archive SQL database. The Industrial Data Bridge service account should have read-only on the WinCC archive and db_datawriter on the ERP SQL target. Do not reuse the WinCC administrator account for either role.

15. Common Errors and Troubleshooting

16. Migration Path to PROFINET and TIA Portal

The 18 S7-315-2DP CPUs cannot be replaced 1:1 by a PROFINET-capable successor without a re-engineering of the line. The recommended successor is the S7-315-2PN/DP (6ES7315-2EH14-0AB0) which keeps the same DP port and adds a PROFINET interface. The WinCC station should be upgraded to WinCC Professional V18 running on TIA Portal and the integration driver switches from PROFIBUS DP to PROFINET IO (channel DLL: PNIODas.dll). Connectivity Pack is replaced by the WinCC Professional OPC UA Server, which is built in and does not require a separate option license. Industrial Data Bridge is replaced by the SIMATIC WinCC / IndustrialDataBridge standalone (no change in install footprint). Refer to the S7-300 manual on Siemens Industry Online Support for spare-part lifecycle information.

17. Field-Proven Caveats

• Do not use the same PLC DB number for the DTM state structure and a high-frequency closed-loop control DB. The DTM scanner reads the DB every 1 s, and the WinCC DB read can stall the OB1 cycle of an S7-315-2DP if the DB is large.
• Do not enable Timestamp to the millisecond on every reason bit. The CPU will time-stamp the bit transitions in OB40, and 32 reason bits × 2 edges/s × 18 PLCs = 1 152 OB40 events per second, which is at the upper limit of the OB40 capacity of an S7-315-2DP (about 2 000 events/s).
• Do not archive Reason bits with a 100 ms scan rate unless the S7-315-2DP is connected via PROFINET, not PROFIBUS. The 100 ms scan generates too much bus traffic at 1.5 Mbit/s.
• Use the DTMDemoProject as a template but rename the project and the database before activating. Re-using the demo database name will cause a name collision in the WinCC archive.
• Always keep the SQL Server on a separate physical or virtual disk from the WinCC OS. Co-locating on the C: drive is the most common cause of the "archive not ready" alarm at shift handover.