Bonfiglioli Vectron CM-PDP Profibus DP Configuration and Debugging Guide

Bonfiglioli Vectron CM-PDP Profibus DP Communication Module Configuration and Debugging Guide

In the field of industrial automation, Profibus DP remains the preferred fieldbus for many factory automation and process control scenarios due to its high real-time performance and determinacy. Bonfiglioli has provided CM-PDP communication modules for its ACTION and ACTION Cube series frequency converters, enabling seamless integration into the Profibus DP network.

Chapter 1: Hardware Installation and Profibus DP Physical Layer Specification

The CM-PDP module, as an extension component of the frequency converter, needs to be installed in slot B of the device. Proper installation and bus networking are prerequisites for stable communication.

1.1 Key points of module assembly

According to the guidelines in Chapter 3 of the manual, the assembly process should pay attention to the following key points:

Safe power-off: Before installing the module, it is necessary to ensure that the frequency converter has completely cut off the power supply and that the DC bus capacitor has been fully discharged (at least wait for 3 minutes).

PE spring grounding: The accompanying PE spring needs to be fixed to the inverter body with M4 screws, and then the communication module should be securely connected to the spring with M2 screws. This step is crucial as it enables a low impedance connection between the Profibus cable shielding layer and the equipment ground (PE), which is the foundation for ensuring EMC performance.

Cover plate treatment: After installation, the pre punched holes on the upper cover plate need to be knocked off to expose the Sub-D 9-pin socket X310.

1.2 Bus Terminal Resistance and Cable Specification

The Profibus DP network requires the activation of termination resistors at the first and last nodes of the physical bus.

Activation method: Implemented through DIP switch S1 on the module (factory default is OFF).

Key warning: Terminal resistance is only effective when the module is powered on. If a terminal node device in the network loses power, its terminal resistance will fail, which may cause the entire bus communication to be interrupted.

Definition of socket: X310 socket follows the standard Profibus DP definition, Pin 3 (RxD/TxD-P, corresponding to line B) and Pin 8 (RxD/TxD-N, corresponding to line A). Special Profibus cables and connectors that meet a transmission rate of 12 MBaud must be used.

Chapter 2: DP Master Station Configuration and PPO Type Selection

The "plug and play" feature of CM-PDP is reflected in its support for Auto-Baud, which does not require manual baud rate setting, but the correct configuration of the main station is the core of communication establishment.

2.1 GSD file import and site address setting

The GSD file (VEC_0696. GSD) is the "ID card" used by the DP master station to identify the attributes of slave station devices.

Import: In the hardware configuration tool (such as Siemens STEP7), install the file through "Extras ->Install new GSD". After installation, the device will be visible in the "PROFIBUS-DP ->Additional Field Devices ->Drives ->ACT 10" directory.

Station address setting: Set the node address through the parameter Profibus Node-ID 391 (range 0-126) of the frequency converter. Note: After the address modification is saved, the frequency converter will automatically perform a reset to apply the new address. In the same Profibus network, the station address of each node must be unique.

2.2 PPO Type Selection and Scanning Cycle

CM-PDP supports four types of PPO (Parameter Process Data Object), corresponding to different data exchange efficiencies (Chapter 7):

PPO1: 4 Words PKW (parameter channel)+2 Words PZD (process data channel), suitable for scenarios that require frequent reading and writing of parameters and moderate real-time requirements, with a scanning cycle of 32ms.

PPO2：4 Words PKW + 6 Words PZD， Provide the richest process data (such as multiple actual values) with a scanning period of 32ms.

PPO3: Only 2 Words PZD, no parameter channel, designed for scenarios that pursue ultimate high-speed data interaction, with a scanning cycle of only 16ms.

PPO4: Only 6 Words PZD, suitable for occasions that only require pure process data communication, with a scanning cycle of 32ms.

In tools such as STEP7, drag and drop the selected PPO objects (such as "PPO2: 4 Words PKW, 6 Words PZD") to the inverter slave station.

Chapter 3: PKW Channel - Inverter Parameter Reading and Writing Mechanism

The PKW (Parameter Identification Value) channel is the essence of the Profidrive protocol, which defines how the master station can read and write access any parameter of the frequency converter through the bus.

3.1 Handshake Rules for Request and Response

PKW's communication follows a strict master-slave "handshake" process (Chapter 10.1.5):

Initial state: The "Task Identifier" (AK) of the master station and the "Response Identifier" (AK) of the slave station are both 0.

Initiate request: The master station writes the task identifier (such as AK=1 for reading parameters, AK=2 for writing integers), and fills in the parameter number (PNU) and index (IND).