Waiting for response: The master station polls and waits for the slave station to change the response identifier from 0 to non-zero (such as AK=1 indicating successful read response, AK=7 indicating execution failure).
End transaction: After the master station reads the data, it writes the task identifier back to 0, and the slave station then resets the response identifier to 0, ending a complete parameter access.
3.2 Key Data Structures
PKE (Parameter Identification): Includes task/response identification (AK) and parameter number (PNU, range 1-999). For example, when accessing parameter 480 (fixed frequency 1), the PNU is 0x1E0.
IND (Index): Used to specify the dataset (DS). For parameters that support dataset switching, IND=1-4 corresponds to datasets 1-4. Key tip: When cyclic writing is required (such as real-time updating of PID setpoint), to avoid burning EEPROM and running out of life, the index value should be incremented by 5 (e.g. IND=6 indicates writing to dataset 1 but only remaining in RAM).
PWE (parameter value): 16 bit parameters occupy PWE1 (low word), 32-bit parameters (such as frequency value) occupy PWE_High+PWE_Low.
3.3 Interpretation of Exception Codes
When the response identifier AK=7 (task cannot be executed), the error code can be read from the low byte of PWE_Low:
1: Invalid parameter number
2: Parameter value exceeds the limit
3: Wrong dataset
9: Inconsistent dataset values (commonly seen when reading IND=0 but different values in four datasets)
101: Parameters cannot be read, etc.

Chapter 4: PZD Channel - Real time Process Data and State Machine Control
The PZD (Process Data) channel is the core of Profibus DP for real-time drive control, which is divided into control word/status word (PZD1) and setpoint/actual value (PZD2-PZD6).
4.1 PZD1: "Three modes" of control word and state machine
The parameter Local/Remote 412 determines the control source of the frequency converter, which mainly involves three modes for Profibus (Chapter 10.2.1):
Mode 0- Contact Control: Controlled by hard wired digital input, PZD1 control word is invalid.
Mode 1- State Machine Control (Recommended): Standard Profidrive Control Mode. Trigger the state machine jump by controlling the combination of word positions.
Startup process: 0x06 (Shutdown) ->0x07 (Switch On) ->0x0F (Enable Operation). This is a universal power on startup sequence.
Shutdown and Emergency Stop: 0x02 triggers Quick Stop, which will use the emergency stop ramp to decelerate. The status word reflects states such as' ready to run ',' operation enabled ', and' fault '.
Mode 2- Remote Contact: Control words Bit 0-5 are directly mapped to virtual digital inputs (S1IND-S6IND), used to simulate hard wired start and stop logic.
Special Reminder (Chapter 10.2.3.2): Transition 5 (from "Operation enabled" to "Ready") can be customized with the parameter State transition 5 392 for shutdown mode:
0: Free Parking (Coast)
1: DC braking (V/f control mode only)
2: Slope deceleration parking (default)
4.2 PZD2-PZD6: Given values and actual values from multiple channels
Calibration of Given Values (Chapter 10.2.5): The given values are sent in standardized form, with -100% corresponding to 0x0000 and+100% corresponding to 0x4000. The reference benchmark is defined by the parameter Profibus Reference 390 (if set to 0, refer to Rated frequency 375). For example, if Profibus Reference=60.00Hz and 0x2000 (50%) is sent, the given frequency is 30.00Hz.
Extended Actual Values (PPO2/PPO4): In PPO2 and PPO4, PZD3-PZD6 maps rich actual values, such as PZD3 for absolute current, PZD4 for active current, PZD5 for warning codes, and PZD6 for fault codes (Chapter 10.2.7).
PPO-OUT data as a global source (Chapter 10.2.8): This is a highly flexible feature. The output data of PZD3-PZD6 in PPO2/PPO4 can serve as a signal source for the internal functions of the frequency converter. For example, PZD3 can serve as a setpoint source for technical controllers, while a certain bit of PZD4 can directly control the digital output.
Chapter 5: SYNC/FREEZE Command and Advanced Diagnosis
5.1 SYNC and FREEZE commands
FREEZE: Synchronize and lock all input data from slave stations, allowing the master station to read device status snapshots at the same time.
SYNC: Synchronize and lock the output data of all slave stations. The master station can configure the output of multiple slave stations, and then use the UNSYNC command to take effect simultaneously, achieving precise synchronization of multi axis motion.
5.2 Troubleshooting and Diagnosis
Status words: Bit 7 (Warning) and Bit 15 (Warning 2) are indicator lights for quickly determining the health status of the device. Warning 2 usually indicates that a trip is about to be triggered.
Communication failure: Fault code F2061 indicates module failure, F2062 indicates DP master station communication interruption (OFF), F2065 indicates configuration error (usually caused by PPO type mismatch).
Actual value monitoring: The two special parameters DP Master OUT 281 and DP Master IN 284 (only available for VPlus software viewing) can intuitively display the raw hexadecimal data of the current bus interaction, making them a powerful tool for locating communication logic problems.