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The Siemens 6AV3688-3AF37-0AX0 SIMATIC HMI Key Panel is a SIMATIC HMI KP8F PN operator panel with eight short-stroke keys, multicolored LEDs and PROFINET communication with PROFIsafe support. It combines local machine operation, status indication and configurable digital signal connections in a compact panel-mounted unit.
Unlike a conventional pushbutton assembly that relies on individually wired operator controls, the KP8F PN integrates the keys and indicator LEDs into a single operator interface. Operators can use it to initiate machine functions, acknowledge operating sequences and identify equipment states through the configured key illumination. The specific behavior of each key and LED depends on the application configuration.
The panel also provides eight configurable digital input/output connections and two safety-related digital input pins. Its PROFINET interfaces support integration with compatible automation systems, while PROFIsafe allows supported safety functions to be incorporated into an appropriately configured safety architecture.
This combination is useful on production machinery where operators need direct access to frequently used commands without a full graphical HMI display. Examples include machine stations, packaging equipment, assembly lines and distributed operator points connected to a PLC-based control system.
| Parameter | Specification |
|---|---|
| Manufacturer | Siemens |
| Model / Order Number | 6AV3688-3AF37-0AX0 |
| Product Family | SIMATIC HMI KP8/KP8F/KP32F |
| Product Type | SIMATIC HMI KP8F PN Key Panel |
| Product Category | Industrial Operator Panel |
| Number of Keys | 8 |
| Key Type | Short-stroke switches |
| Key Indicators | Multicolored LEDs |
| Communication Interface | PROFINET |
| Integrated Ethernet Interfaces | 2 |
| Integrated Switch | Yes |
| Safety Communication | PROFIsafe |
| Configurable Digital Connections | 8 DI/DO |
| Safety-Related Digital Inputs | 2 |
| Supply Voltage | 24 V DC |
| Configuration Software | STEP 7 V5.5 or later, subject to the applicable configuration requirements |
| Front Protection Rating | IP65 |
| Rear Protection Rating | IP20 |
| Mounting Type | Panel mounting |
| Dimensions | 98 × 155 × 49 mm |
| Weight | 0.324 kg |
The KP8F PN converts operator actions into control signals and presents operating feedback through its integrated LEDs. When an operator presses a configured key, the panel processes the input and communicates the corresponding information through the configured automation interface. The PLC then determines the appropriate response according to the machine program.
The LEDs provide visual feedback associated with the programmed machine state. For example, a key may indicate that a machine function is available, active or waiting for a required condition. These indications depend on the PLC logic and panel configuration; the same key does not have a fixed universal meaning across all installations.
PROFINET carries communication between the panel and the automation system. The integrated Ethernet switch supports network arrangements appropriate to the configured topology. The available digital connections can also be used according to the panel’s supported I/O configuration.
For safety-related applications, PROFIsafe communication must be configured within a compatible safety system. The presence of safety-related inputs and PROFIsafe support does not by itself make a machine function safe. The complete application must include the appropriate safety controller, devices, configuration and validation.
The 6AV3688-3AF37-0AX0 acts as a local operator interface between personnel and the machine-control system. It combines physical key operation, visual feedback and industrial communication in one panel.
Operator Input → KP8F PN Key Panel → PROFINET / PROFIsafe Communication → PLC or Safety Controller → Machine Actuators and Status Feedback
| System Component | Function | Relationship to the KP8F PN |
|---|---|---|
| 6AV3688-3AF37-0AX0 KP8F PN | Provides key operation, LED indication and communication | Serves as the local operator interface |
| SIMATIC PLC | Executes machine-control logic | Processes operator commands and returns status information |
| Safety Controller | Executes configured safety logic | Handles safety-related functions through a compatible PROFIsafe architecture |
| PROFINET Network | Exchanges cyclic and diagnostic data | Connects the panel to compatible automation devices |
| Integrated Ethernet Switch | Supports network connections | Enables supported line or ring arrangements |
| Digital Input/Output Signals | Exchange discrete electrical signals | Use the panel’s configurable I/O connections where applicable |
| Emergency-Stop or Safety Devices | Initiate safety-related responses | Must be selected and integrated according to the machine’s risk assessment |
| Machine Sensors | Report position, presence or operating conditions | Supply process information to the PLC or safety controller |
| Machine Actuators | Execute control commands | Respond to the control system rather than directly to the panel alone |
| Engineering Software | Configures the panel and automation system | Defines key behavior, communication and applicable safety parameters |
| Application | Typical Equipment | Role of the KP8F PN |
|---|---|---|
| Packaging Machinery | Filling, sealing and wrapping equipment | Provides direct access to frequently used machine commands |
| Assembly Automation | Automated assembly stations | Supports local operation and visual status indication |
| Manufacturing Lines | Distributed operator stations | Gives operators access to configured functions at individual stations |
| Material Handling | Conveyors and transfer equipment | Supports local commands and operating-state feedback |
| Machine Tools | Automated production machines | Provides panel-mounted key operation for selected functions |
| Robotic Workcells | PLC-controlled robotic stations | Supports configured operator interaction within the cell |
| Industrial Control Cabinets | Machine-level control panels | Combines key operation and network communication in a panel-mounted unit |
| Safety-Related Automation | Machines with compatible safety controllers | Supports configured PROFIsafe communication as part of a validated safety architecture |
| Component | Function | Relationship to the KP8F PN |
|---|---|---|
| SIMATIC PLC | Executes machine-control logic | Processes operator inputs and supplies operating status |
| SIMATIC F-CPU | Executes safety-related control logic | Supports compatible PROFIsafe applications |
| PROFINET Cable | Carries industrial Ethernet communication | Connects the panel to the automation network |
| 24 V DC Power Supply | Supplies operating power | Powers the panel according to its electrical requirements |
| Digital Input/Output Devices | Exchange discrete signals | Interact with the configured digital connections |
| Emergency-Stop Devices | Initiate emergency-stop functions where required | Must be integrated into the appropriate safety circuit |
| Safety Sensors | Detect hazardous conditions or machine states | Supply signals to the safety-control architecture |
| Machine Sensors | Detect process conditions | Provide information used by the PLC |
| Machine Actuators | Perform physical machine operations | Execute commands issued by the control system |
| Engineering Software | Configures communication and application behavior | Defines the panel’s key functions and system integration |
| Model / Product | Product Type | Relationship | Selection Consideration |
|---|---|---|---|
| Siemens 6AV3688-3AY36-0AX0 | SIMATIC HMI KP8 PN Key Panel | Related eight-key panel with PROFINET communication | Consider when PROFIsafe functionality is not required and verify the digital I/O configuration |
| Siemens 6AV3688-3EH47-0AX0 | SIMATIC HMI KP32F PN Key Panel | Related key panel with 32 short-stroke keys and PROFIsafe support | Consider when the application needs more operator keys |
| Siemens 6AV3688-3XY38-3AX0 | SIMATIC HMI KP8 Empty Front | Empty front design for standard 22.5 mm operator controls | Consider for a modular operator panel using compatible standard controls |
| Siemens SIMATIC S7-1200 | PLC Family | Automation controller family | Verify the required PROFINET and safety architecture for the application |
| Siemens SIMATIC S7-1500F | Fail-Safe PLC Family | Potential safety-control platform for compatible applications | Select according to the safety requirements and complete system design |
The KP8F PN supports PROFIsafe communication and includes safety-related digital input connections. The standard KP8 PN variant has a different functional configuration, so the required safety functions and I/O arrangement should be checked before choosing between them.
Yes. Key behavior and associated LED indications depend on the configured automation project. The PLC logic, communication setup and panel configuration determine what each key does and how its status is displayed.
The panel has two industrial Ethernet interfaces and an integrated switch, supporting suitable network arrangements such as line or ring topologies. The final topology must be planned around the network requirements and connected devices.
No. PROFIsafe support is only one part of a safety architecture. A compatible safety controller, correctly selected safety devices, appropriate configuration and validation of the complete safety function are still required.