Configuring PROFIBUS DP Master Class 2 Communications in PCS 7 with CP 5613

In SIMATIC PCS 7, configuring a PC station as a PROFIBUS DP Master Class 2 (DPM2) using a CP 5613 PCI/PCIe communication processor enables acyclic DP-V1 parameterization, device diagnostics, and asset management (via SIMATIC PDM or OPC Scout) without disrupting cyclic Master Class 1 (DPM1) control. In STEP 7 HW Config, insert a SIMATIC PC Station containing the CP 5613, connect it to the same PROFIBUS DP subnet as the S7-400 CPU, assign a unique PROFIBUS address (e.g., address 1 or 2), set its operating mode to 'DP' with Master Class 2 properties, and activate DP-V1 acyclic services. On the physical PC, install SIMATIC NET PC Software, configure the Station Configuration Editor to match HW Config slot indexes, and set the PG/PC Interface to 'CP5613(PROFIBUS)'. Validate hardware order numbers with an authorized Siemens distributor or the Siemens Industry Mall.

Executive Summary

In complex process manufacturing facilities, field instrumentation—such as HART transmitters, smart valve positioners, and variable frequency drives—communicates over PROFIBUS DP or PROFIBUS PA. While the primary automation controller (e.g., AS 410-5H or CPU 414-4H) acts as the cyclic Master Class 1 (DPM1), field maintenance personnel require acyclic diagnostic access for calibration, valve travel profiling, and device health monitoring. Configuring a PC station equipped with a CP 5613 processor as a Master Class 2 (DPM2) station allows SIMATIC PDM or custom OPC client applications to interact with field instruments in parallel with the controller. This guide outlines the complete hardware configuration, SIMATIC NET setup, and network engineering rules required to establish reliable DPM2 communication.

Architecture and Fundamental Mechanics

The PROFIBUS DP standard (IEC 61158 / IEC 61784) specifies distinct master hierarchies operating concurrently on a single physical bus:
1. Master Class 1 (DPM1) vs Master Class 2 (DPM2):
- Master Class 1 (DPM1): The automation controller (PLC). Executes deterministic, high-speed cyclic I/O data exchange (inputs/outputs) with slave devices at fixed scan intervals.
- Master Class 2 (DPM2): Engineering stations, diagnostic consoles, or asset management servers (e.g., SIMATIC PDM). Executes acyclic DP-V1 communication services (Read Record, Write Record, Alarm Acknowledge) on request.
2. Bus Token Passing and Multi-Master Synchronization:
- PROFIBUS DP uses a hybrid access method: a logical token ring among active masters, combined with master-slave polling.
- The S7-400 CPU and the CP 5613 pass the bus access token back and forth. The token rotation time (T_tr) must be sufficiently sized in HW Config network settings to allow both the DPM1 cyclic scan and DPM2 acyclic message slots without triggering bus timeouts.
3. CP 5613 Hardware and SIMATIC NET Architecture:
- The CP 5613 (e.g., CP 5613 A2 / CP 5613 A3) possesses an onboard microprocessor that autonomously manages PROFIBUS protocol execution.
- SIMATIC NET exposes this hardware through the DP-V1 / DP Master interface or OPC Server (OPC.SimaticNET).

Step-by-Step Implementation Procedure

Configure the PC Station in STEP 7 HW Config:
a. In SIMATIC Manager, right-click the Multiproject and select Insert New Object -> SIMATIC PC Station.
b. Name the PC station to match the physical computer's Windows hostname.
c. Open HW Config for the PC Station.
d. From the Hardware Catalog, navigate to SIMATIC PC Station -> CP PROFIBUS -> CP 5613 A2/A3 and place it in Slot 1 (matching the Station Configuration Editor index).
e. Place an Application or OPC Server object in Slot 2.
Assign PROFIBUS Parameters and Subnet Connection:
a. In the CP 5613 object properties, select the 'General' tab and click Properties under Interface.
b. Connect the CP 5613 to the existing PROFIBUS DP subnet shared with the S7-400 AS.
c. Assign a unique PROFIBUS Address (e.g., Address 1 or 2). Never assign Address 0 (reserved for PG) or collide with the CPU (typically Address 2) or slave addresses.
d. Under 'Operating Mode', select DP Master.
e. In the DP Master properties, verify that DP-V1 services are enabled.
Calculate Bus Parameters in NetPro:
a. Open NetPro for the Multiproject.
b. Select the PROFIBUS DP subnet line and open 'Properties -> Network Settings'.
c. Select the profile (typically 'DP' or 'User-Defined') and click Bus Parameters....
d. Verify that the Highest Station Address (HSA) is greater than the CP 5613 address.
e. Allow STEP 7 to recalculate T_tr (Target Token Rotation Time) to account for multiple masters.
f. Save and compile network connections.
Configure Physical PC Station with Station Configuration Editor:
a. On the PC containing the CP 5613, open Station Configuration Editor.
b. Add the CP 5613 to Index 1 and Application / OPC Server to Index 2, matching HW Config.
c. Open Windows Control Panel, select Set PG/PC Interface, and set the access point S7ONLINE (or CP_L2_1:) to PC internal.local.1.
Download Configuration to the PC Station:
a. In SIMATIC Manager, select the PC Station object.
b. Select PLC -> Download to transfer the hardware configuration to the Station Configuration Editor.
c. Confirm that the Station Configuration Editor status shifts to 'RUN' with all components displaying pencil/gear icons.

Verification

Open SIMATIC NET -> Communication Settings on the PC: verify the CP 5613 displays status 'Operational' on the PROFIBUS subnet.
Open OPC Scout or SIMATIC PDM: browse the PROFIBUS DP network tree.
Execute an acyclic read (e.g., read device serial number or calibration data via DP-V1 Read Record): confirm valid data returns without causing bus errors on the S7-400 cyclic master.

Limitations and Operational Precautions

Adding an active Master Class 2 station increases the PROFIBUS token rotation time (T_tr). On high-speed motion or fast cyclic I/O segments, verify that increased bus cycle times remain within process latency tolerance.

Engineer FAQ

What is the difference between a DP Master Class 1 and Master Class 2?

Master Class 1 (PLC) executes cyclic process data exchange with I/O slaves. Master Class 2 (PC/PG) performs acyclic diagnostics, parameterization, and maintenance.

Can a CP 5613 Master Class 2 coexist with an S7-400 CPU on the same bus?

Yes. PROFIBUS DP supports multi-master architectures using token passing between Master Class 1 and Master Class 2 stations.

What PROFIBUS address should be assigned to the CP 5613?

Assign a unique address (such as 1 or 2) that does not conflict with controllers, field slaves, or temporary programming devices (PG address 0).

Does Master Class 2 communication disrupt normal PLC control?

No, acyclic DP-V1 requests execute in dedicated token time slots without halting or delaying cyclic I/O scans, provided bus parameters are properly calculated.