Key Takeaway
In Siemens PLC terminology, CP stands for Communication Processor. CP modules in S7-1500 extend communication capabilities beyond the standard Ethernet/Profinet ports. They enable connections like Industrial Ethernet with redundancy (CP 1543-1), secure remote access via VPN, connection to cloud services, or interfaces like Modbus TCP/RTU, MQTT, or S7 communication over wider networks. CP modules improve cybersecurity, enabling encrypted communication (TLS, VPN tunnels), firewall capabilities, and secure cloud integration. This makes CP modules vital in distributed or IIoT-based automation environments. CPs plug into the S7-1500 rack, seamlessly integrating into the PLC program within TIA Portal, offering flexible, secure communication in modern automation systems.
Definition and Purpose of Communication Processors (CP)
A Communication Processor, commonly called CP, is a dedicated module designed to manage communication tasks for Siemens S7-1500 PLCs. Unlike the onboard communication interfaces available on CPUs, CPs offer enhanced data transfer capabilities, dedicated processing power, and support for more complex communication protocols.
In simple terms, a CP allows your automation system to talk fluently with other industrial systems. It handles large volumes of data efficiently and maintains consistent performance, even in heavily networked environments.
The real advantage? It offloads communication load from the CPU, ensuring your main program cycle remains undisturbed. For large plants or systems with high-speed data exchange needs, CPs become indispensable.
Whether it’s connecting to an external SCADA system, an ERP backend, or multiple PLCs, a CP is what makes industrial integration seamless.
Types of CPs Available for S7-1500
Siemens offers several types of Communication Processors for the S7-1500 series, depending on the protocol and performance requirements. The most common are:
CP 1542-1: For Industrial Ethernet communication. Ideal for connecting S7-1500 to SCADA, HMI, or other controllers over Ethernet.
CP 1542SP-1: A space-saving variant for the ET 200SP system, also supporting Ethernet-based networks.
CP 1543-1: Adds advanced features like encryption (TLS), firewall functions, and secure communication for higher security demands.
CP 1543SP-1: The secure version for ET 200SP applications.
These CPs vary by number of connections, security features, supported protocols, and data throughput. Some models are optimized for Profinet or Profibus as well.
Choosing the right CP depends on your architecture—whether you need rugged cyber security, distributed I/O control, or just high-speed Ethernet connections.
Applications for Industrial Ethernet, Profibus, and Profinet CPs
Each type of CP module is built for a specific set of industrial communication needs:
Industrial Ethernet CPs are perfect when you’re working with SCADA systems, data logging servers, or OPC UA applications. Their speed and versatility are unbeatable.
Profinet CPs integrate seamlessly with Profinet IO devices. If you’re setting up distributed automation systems, these are your go-to.
Profibus CPs are crucial for legacy systems or industrial machines that still rely on Profibus networks. They help bridge the old and new.
In most large-scale manufacturing environments, you’ll see a mix of these. CPs allow your S7-1500 PLC to act as the central controller, efficiently handling data exchange across multiple layers of your factory.
For example, using a CP 1543-1, you can run secure HTTPS data transfers from your PLC to cloud-based dashboards, without burdening your main CPU.
How to Configure CPs in TIA Portal
Setting up a CP in Siemens TIA Portal is straightforward, but there are a few things to keep in mind. Once the CP is added to your hardware configuration, you can start configuring its IP address, communication partners, and security settings.
You can define:
IP addresses and subnet masks
Firewall rules and access lists (for secure CPs)
Connection resources and protocols (like S7 communication, OPC UA, HTTPS)
It’s essential to assign the CP to the correct rack slot and configure the network topology correctly. In larger networks, defining communication relationships between PLCs or with an HMI becomes easier using the graphical network view.
TIA Portal also allows you to simulate and test these configurations before deploying, which helps reduce commissioning time significantly.
Common Use Cases in Distributed Control Systems
Distributed control is where CPs shine. When one S7-1500 PLC needs to communicate with multiple sub-systems across a plant, CPs enable this through structured, scalable communication paths.
Typical scenarios include:
Remote access to PLCs from a central control room
Logging process data to central servers
Running time-critical interlocks across machines via Profinet IO
Enabling cloud connectivity for Industry 4.0 initiatives
For instance, a CP 1542-1 can be used to interface a main S7-1500 CPU with both HMI panels and other distributed PLCs. Meanwhile, a CP 1543-1 ensures that this communication is secure and compliant with IT policies.
You can scale your automation system smoothly without overloading any single component. That’s the power of modular communication.
Conclusion
Communication Processors are the unsung heroes of modern automation systems built on the S7-1500 platform. They provide the backbone for robust, scalable, and secure communication in industrial environments.
From Industrial Ethernet to Profinet and Profibus, Siemens offers a wide range of CP modules to suit different needs. Whether you’re an automation engineer working on a new factory line or maintaining a legacy system, integrating the right Communication Processor ensures your PLC network runs smoothly.
In short, if you want your S7-1500 setup to be smart, fast, and future-ready — a CP is not optional. It’s essential.